use gesture to switch home screen and drawer. there is still a bug.
Merge remote-tracking branch 'origin/master' into suyu_issue55

Conflicts:
	launcher/src/com/cooeeui/brand/zenlauncher/Launcher.java
fix the bug, and use a black background.
Merge pull request #59 from cooee-zen/suyu_issue55

Suyu issue55: swipe up and down to switch workspace and drawer.