Merge pull request #398 from zoodles/master

Pull request from Zoodles team
When changing the density, update existing DisplayMetrics instance.
Merge branch 'master' of https://github.com/pivotal/robolectric
Fix NPE
Added support for line count in ShadowTextView
Added support for getters and setters of X and Y on ShadowView
Merge branch 'master' of https://github.com/pivotal/robolectric