[1/2] added Slim Recents as option

take reference add OmniSwitch as defaul recents by @Maxwen (Omnirom)

- make slim Recents as option between Aosp/OmniSwitch
- add a warning dialog when selecting

PS3: Rebase
PS4: Fix Settings.java derp
PS5: Set to private boolean as suggested by Tianrui
PS6: Rebase
PS7: Rebase
PS8: fix derp
PS9: Rebase && derp in a statement in BaseStatusBar.java
PS10: Another derp
PS11: Remove unneeded import from rebase
PS12: Derp fix
PS13: Another derp fix
PS14: Derp-o-rama
PS15: Rebase
PS16: Again another derp
PS17: rebase
PS18: fixed

Change-Id: I9d43f2e5a29ec9c29d172915a14a101907b93ac5

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java