Update .gitignore

Cleaned up and consolidated some things, mostly to make things easier on IntelliJ/Android Studio
Update gradle plugin to latest 1.0 RC, add local gradle wrapper to easy project import
Cleanup and update build.gradle files for modules

* Updates plugin names to new versions (previous versions were deprecated and will break soon)
* Update build and compile SDK versions to latest
* Remove unnecessary gradle plugin version and repositories declarations, as these are set via the top-level build.gradle file
* Update target SDK version to latest 21
* Specify min and target SDK versions that match the manifests

Tested the sample and everything still works as normal :)
Update README.md to use syntax highlighting in code samples