Replaced Theme.Sherlock.Light.Dialog with Theme.Dialog

Unable to build against the latest version of ABS 4.3.1 due to removal of Dialogs from ABS in version 4.3.0

ABS removed dialog themes 6 months ago in version 4.3.0: https://github.com/JakeWharton/ActionBarSherlock/commit/601bde214b56b8fad0b4fc5aaed5af0b531b6135

Also similar issue/solution for reference: http://stackoverflow.com/a/16586113