Early attempts at testing RBLResixableImage
Fix dem tests
Add tests to verify the correct asset it used

@2x versus @1x
Merge remote-tracking branch 'origin/master' into rblresizableimage-tests
Tests improvements and possible fix for #79
Remove the -writeToFile:
Add assertions to check we have the blue border
Merge pull request #81 from github/rblresizableimage-tests

Fix RBLResizableImage to use @1x representation for @1x contexts