add OWNERS to okhttp

Test: build/make/tools/checkowners.py -c -v OWNERS
Change-Id: I71adadb74e669ad81258f38de4f4a1dfccffa6fc
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..5b9c6ec
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,3 @@
+nfuller@google.com
+tobiast@google.com
+android-libcore-team+review@google.com