Changed plugin group and package names.

Now uses package 'com.android.build.gradle' for source,
and group 'com.android.build'.

The packages for the test applications have not been changed, yet.

Change-Id: Id55eb9ea91295c72d989844b1f1cdee1ca9b58c3
diff --git a/.gitignore b/.gitignore
index 34bf374..6e31dc8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,5 +3,8 @@
 *.ipr
 *.iws
 .gradle
-build
+/build
+gradle/build
+testapps/*/build
+testapps/multiproject/*/build
 /repo