Gradle Android Plugin & Catkinization

Looks like alot but not actually that much going on here. No code changes, just build environment changes.

**Gradle Android Plugin**

Moved files and folders to the new default layout for an android project:

* java code moved -> `src/main/java`.
* AndroidManifest.xml -> `src/main`
* `res` -> `src/main`
* Delete project.properties, ant.properties, local.properties, build.xml
* Update `build.gradle` files with android project information.
* Update gradle to 1.6 (req'd for android plugin v0.4.1).

**Catkinization**

Updated to work with [rosjava_tools](https://github.com/ros-java/rosjava_tools) which uses a single macro:

`catkin_android_setup()`

that sets up a dummy target for calling on `gradlew assembleXXX install` and adds cross-repo dependencies from the `package.xml`.