Improve gradle support.
Fix issue #18
Merge branch 'master' of https://github.com/lewisjdeane/L-Dialogs

Conflicts:
	app/src/main/java/uk/me/lewisdeane/ldialogs/CustomListDialog.java
Fix wrong merge
Add ability to set the positive button background.
Merge branch 'master' of https://github.com/lewisjdeane/L-Dialogs

Conflicts:
	app/src/main/java/uk/me/lewisdeane/ldialogs/CustomDialog.java
Merge pull request #28 from StephaneBg/master

Correct issue #26