Revert "Bumping build tools version."
Revert "Bumping build tools version."

Reverting because 23.1.0 for some reason wasn't available via the Stable channel of Android Studio on Windows as of current.

This reverts commit cd831ec479fd3ec57aa8b41bc0a1fa02991efc4e.

Change-Id: Ibe316b6dc42504f8ef3796bd024d45079ab52e10

googlecodelabs/android-perf-testing,googlecodelabs/android-perf-testing