Update packaging of the gradle-built support lib.

Put a top level folder in the zip archive.
Change the name of the generated archive to android-m2repository-x.y.z

Change-Id: I657204ee10ec0aa5ec5eeacb7b1a2ecc63b249ce
diff --git a/build.gradle b/build.gradle
index e6e78f9..31fb405 100644
--- a/build.gradle
+++ b/build.gradle
@@ -38,7 +38,8 @@
 task createArchive(type: Zip, dependsOn: mainUpload) {
     from project.ext.supportRepoOut
     destinationDir project.ext.distDir
-    baseName = "support-${project.ext.supportVersion}"
+    into 'm2repository'
+    baseName = "android-m2repository-${project.ext.supportVersion}"
 }
 
 // prepare repo.