SystemUI: SlimDim performance boost

some code optimization to make SlimDim run smoother and get rid
of the lags

patchset 1: reduced findViewById calls, wrapped search for parent
            view in a Runnable, removed keyguard checks
patchset 3: made onNavButtonTouched called after home button
            transition ends, instead of every button
patchset 5: switching battery saver on now disables SlimDim

AICP'fied by replacing R.id.home with NavbarEditor.NAVBAR_HOME

Change-Id: Ifa831d640518d215675dc621afcef2f507e408ea
2 files changed