Move setting maven group directly to each build.gradle.

Test: ./gradlew buildOnServer
Change-Id: If83e8d3d4bb8c9dd260f65c3898b6f0fa8ffc524
diff --git a/percent/build.gradle b/percent/build.gradle
index fc6282b..a1d540d 100644
--- a/percent/build.gradle
+++ b/percent/build.gradle
@@ -1,3 +1,5 @@
+import android.support.LibraryGroups
+
 plugins {
     id("SupportAndroidLibraryPlugin")
 }
@@ -22,6 +24,7 @@
 supportLibrary {
     name = "Android Percent Support Library"
     publish = true
+    mavenGroup = LibraryGroups.SUPPORT
     inceptionYear = "2015"
     description = "Android Percent Support Library"
     legacySourceLocation = true