Upgrade to official build tools 1.0 and add gradle wrapper.

The wrapper is for people who might be on Windows or not used to a gradle build system. They can just run commands with ./gradlew instead of having to install gradle themselves.

Sorry for so many PR's so quickly! Not sure if you wanted them in bigger pieces or smaller ones :\
I just removed it all together. It always gets replaced by the value in the `build.gradle` file anyways.