Add MessageList activity

* Add MessageList Activity class and Manifest entry
* Add appropriate layouts, views, etc.
* Wire into FolderMessageList

Lots to do, but this gives us a useable screen.
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 8c742cd..250c78a 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -121,6 +121,11 @@
                 <action android:name="android.intent.action.MAIN" />
             </intent-filter>
         </activity>
+        
+        <activity
+            android:name=".activity.MessageList">
+        </activity>
+                
         <activity
             android:name=".activity.MessageView"
             android:theme="@android:style/Theme.NoTitleBar" >