OmniSwitch: Allow open app as floating window

Since i am using OmniSwitch to activate an app as
floating window, i am recommitting this commit so it
can be adjusted and rebased if needed.

PS 6: Rebased:
      Conflicts: rc/org/omnirom/omniswitch/ui/SwitchGestureView.java

Conflicts:
	src/org/omnirom/omniswitch/SwitchManager.java

Change-Id: If4dbb4c99113a4a51bc78eb3a4a1447bf8d22fda