Initial gradle sync fixed

[pavelbazika]

When the project is cloned, initial gradle sync fails with

Could not find aapt2-proto.jar (com.android.tools.build:aapt2-proto:0.3.1). Searched in the following locations: https://jcenter.bintray.com/com/android/tools/build/aapt2-proto/0.3.1/aapt2-proto-0.3.1.jar

As can be found, google() maven repository needs to be the first one in build.gradle.