update gradle to 1.0

@mimming please review
Since you're not using a snapshot any more, and geofire is findable by Maven / Gradle - http://search.maven.org/#artifactdetails%7Ccom.firebase%7Cgeofire%7C1.1.0%7Cjar the readme should be updated to indicate that the dependency should be fetched normally (no local GeoFire build is necessary).  

This might also be a good chance to enhance the setup instructions (e.g. link to the manifest from the readme so drive-by viewers know how much they'll have to update to get the project working)