New OnceUx Test Class CompanionAdTestCase.java

##Rationale
Now that Companion Ads have been implemented into the Sample App, It's time for tests.
##Changed Files
**CompanionAdTestCase.java**
* New utility methods
    * *companionCheck* finds the companion ad based on the companion ad frame's resource id
    * *toCompanionAdCheck(int msec)* navigates to the next ad break, then performs *companionCheck*. It returns the results of *companionCheck*.
    * *toEndOfAdBreak* navigates to the end of an ad break, hides the seek controls, and then performs *companionCheck*. It returns the results of *companionCheck*.
* New tests
    * **testCompanionAd** navigates through the video using *toCompanionAdCheck* and *toEndOfAdBreak*. After the start of each ad break, it asserts that the companion ad is present.
    * **testCompanionAdLink** clicks on a companion ad and tests for the presence of the browser url the click is meant to link to
    * **testCompanionAdVanish** navigates through the video using *toCompanionAdCheck* and *toEndOfAdBreak*, checking after the end of each ad break for the presence of a companion ad. It asserts that *toEndOfAdBreak* will return false for each ad break.
I've never run into any troublesome issues. When I use waitUntilGone and waitForExists, the tests perform exactly like they were meant to, and at their end the test runner jumps right into the tearDown and moves right along to the next test. Should they have crashed UiAutomator or something equally catastrophic, the tearDown would absolutely crash.

I don't know the exact intricacies of how they work in comparison to other timeout methods, but waitForExists keeps an eye out for a particular UiObject, and when it exists (is visible), the timeout gets interrupted, and the method returns true. If the object does not exist at the end of the given timeout, it returns false. waitUntilGone essentially functions the same, but with the opposite intention - the timeout gets interrupted and returns true if the UiObject disappears, and it will return false if it remains at the end of the timeout. If you're interested in the documentation, here it is:
http://developer.android.com/tools/help/uiautomator/UiObject.html#waitForExists(long)