POM: improve profiles

1) Move FindBugs and PMD report generation to a separate profile - findfugs
2) dynamically choose maven-site-plugin version for M2 or M3
diff --git a/pom.xml b/pom.xml
index c62bcdf..409d55e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -225,16 +225,6 @@
                     </instructions>
                 </configuration>
             </plugin>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>findbugs-maven-plugin</artifactId>
-                <version>2.4.0</version>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-pmd-plugin</artifactId>
-                <version>2.6</version>
-            </plugin>
         </plugins>
     </build>
     <reporting>
@@ -297,26 +287,6 @@
                     </reportSet>
                 </reportSets>
             </plugin>
-            <plugin>
-                <groupId>org.codehaus.mojo</groupId>
-                <artifactId>findbugs-maven-plugin</artifactId>
-                <version>2.4.0</version>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-pmd-plugin</artifactId>
-                <version>2.6</version>
-                <configuration>
-                    <linkXref>true</linkXref>
-                    <sourceEncoding>utf-8</sourceEncoding>
-                    <minimumTokens>100</minimumTokens>
-                    <targetJdk>1.5</targetJdk>
-                    <excludes>
-                        <!--exclude>**/*Bean.java</exclude-->
-                        <exclude>**/external/*.java</exclude>
-                    </excludes>
-                </configuration>
-            </plugin>
         </plugins>
     </reporting>
     <profiles>
@@ -382,13 +352,75 @@
             </build>
         </profile>
         <profile>
-            <id>m3</id>
+            <id>findbugs</id>
             <build>
                 <plugins>
                     <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>findbugs-maven-plugin</artifactId>
+                        <version>2.4.0</version>
+                    </plugin>
+                    <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-pmd-plugin</artifactId>
+                        <version>2.6</version>
+                    </plugin>
+                </plugins>
+            </build>
+            <reporting>
+                <plugins>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>findbugs-maven-plugin</artifactId>
+                        <version>2.4.0</version>
+                    </plugin>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-pmd-plugin</artifactId>
+                        <version>2.6</version>
+                        <configuration>
+                            <linkXref>true</linkXref>
+                            <sourceEncoding>utf-8</sourceEncoding>
+                            <minimumTokens>100</minimumTokens>
+                            <targetJdk>1.5</targetJdk>
+                            <excludes>
+                                <exclude>**/external/*.java</exclude>
+                            </excludes>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </reporting>
+        </profile>
+        <profile>
+            <id>maven-3</id>
+            <activation>
+                <file>
+                    <!-- This employs that the basedir expression is only 
+                        recognized by Maven 3.x (see MNG-2363) -->
+                    <exists>${basedir}</exists>
+                </file>
+            </activation>
+            <build>
+                <pluginManagement>
+                    <plugins>
+                        <plugin>
+                            <groupId>org.apache.maven.plugins</groupId>
+                            <artifactId>maven-site-plugin</artifactId>
+                            <version>3.0</version>
+                        </plugin>
+                    </plugins>
+                </pluginManagement>
+                <plugins>
+                    <plugin>
                         <artifactId>maven-site-plugin</artifactId>
-                        <version>3.0-beta-3</version>
+                        <executions>
+                            <execution>
+                                <id>attach-descriptor</id>
+                                <goals>
+                                    <goal>attach-descriptor</goal>
+                                </goals>
+                            </execution>
+                        </executions>
                     </plugin>
                 </plugins>
             </build>