UI Automator goal

Hi all,

here is a pull request to add a ui automator goal to launch UI tests on android.

Can execute tests using ui uiautomator.

Implements parsing parameters from pom or command line arguments and sets useful defaults as well. This goal is meant to execute a special _java project_ dedicated to UI testing via UIAutomator. It will build the jar of the project, dex it and send it to dalvik cache of a rooted device or to an emulator. If you use a rooted device, refer to <a href="http://stackoverflow.com/a/13805869/693752">this thread on stack over flow</a>.

The tests are executed via ui automator. A surefire compatible test report can be generated and its location will be logged during build.

To use this goal, you will need to place the uiautomator.jar file (part of the Android SDK > 16) on a nexus repository.

A typical usage of this goal can be found at <a href="https://github.com/stephanenicolas/Quality-Tools-for-Android">Quality tools for Android project</a>.
 
see <a href="http://developer.android.com/tools/testing/testing_ui.html">Android UI testing doc</a>
see <a href="http://developer.android.com/tools/help/uiautomator/index.html">UI Automator manual page</a>