Beginnigs of a Wear app

This is very much still a work-in-progress, and you probably shouldn't merge it as-is.  I would like to get reviews for it in the meantime, but I am fixing a couple things as I go along.

Known issues with this changeset:
  * I used the default "robot" icon for everywhere that needed an icon in the Wear app.
  * The Wear app is still launchable, and launches the "Hello, {square,round} world!" activity.
  * I still haven't figured out the correct threading for the handheld app — in particular, updates to the wearable via mergeEstimate() happen on a service thread, but deleting the notification altogether happens on the main thread.  This is probably racy, but it didn't bite me when I used the app today.
  * I haven't done any of the packaging work. The deployment strategy is to push the wearable app to the device via ADB; the automatic installation from the handheld app is yet to be added.

I did have to upgrade holoeverywhere to get it to build (for reasons I can't quite remember, but maybe for the support library JAR that needs to be copied around), which had a trickle-down effect of needing to get rid of ActionBarSherlock too.

You should be able to build the wearable project by simply "Importing" `wearable/build.gradle` in Android Studio.