Utilize AOSP's new Volley http caching library

Three reasons for this move

1) App can't maintain a dependancy to ROMControl
2) We can't include Koush's UrlImageViewHelper in both ROMControl
     and mGerrit.
3) Volley is being announced this week at #IO13 and this provides
     a simple implementation usage example. I noticed while searching
     open source examples of usage are non existant, at least
     the only info I could find about it was the announcment. So
     here is one example of usage specific to Images and ImageViews

Change-Id: Ibc9aa917606dd4a40ef44ab7294b86454a99de5a
Merge "Utilize AOSP's new Volley http caching library"