bring back DPI changer

PS4:Added situation that values don't exists in build.prop
PS5:
After hour of play with this condition in IntelliJ IDEA I finaly found solution for it.
I must compare .lengtg() to 0. Now it works.
Still I think, that we need clean up all dialog, because clearing Market stuff is no logner needed.

Change-Id: I3e3a63eb64b0f107c1fad0f2fd8bb7c7f6e6e227
Signed-off-by: ChampionSwimmer <android@championswimmer.tk>

Conflicts:

	src/com/aokp/romcontrol/fragments/UserInterface.java