Updating build tools and minSdk.
Updating build tools and minSdk.

Bug: 28192328
Change-Id: I8b41bc0ce12caf00731a0c949e83fdacb1cc2b85

WeRockStar/iosched,epiphany27/iosched,jarekankowski/iosched,amardeshbd/iosched,google/iosched,amardeshbd/iosched,WeRockStar/iosched,amardeshbd/iosched,epiphany27/iosched,google/iosched,jarekankowski/iosched,jarekankowski/iosched,amardeshbd/iosched,WeRockStar/iosched,google/iosched,epiphany27/iosched