DevMode: delegate module directory updates to SuperDevMode

When -superDevMode is turned on, launch SuperDevMode with a -launcherDir
argument pointing to the right place, and stop updating the nocache.js
file directly.

This should also fix issues with public resources not being
updated and nocache.js.gz file not being deleted.

Also, extracted helper methods from the SuperDevListener constructor.

Change-Id: Ie3afb2612a6ef861db078ea2b9540bfa2d92be06