Initial commit for build.gradle

- Migrate COOJA source and some apps to a standard directory layout
- Can download dependencies dynamically
- Can check style (Android style guide)
- Can generate configuration files for idea and eclipse IDE
- Adding gradle build files to .gitignore
- Removed all bundled libraries
- All regression tests are now using gradle to build cooja
- Migrated apps to gradle for building (embedded libs have been removed)
- run commands are now available as well. For instance to limite max
  Heap memory