Checked in a new DemoGearsStore.js class. DemoGearsStore is based on
Brad's GearsStore code, with two additional features: you now can
specify a database name as a constructor arg, and you now can revert a
database to the restore the original document data.
Changed World.js to use DemoGearsStore instead of ItemFileWriteStore.
Added a few new methods: isInDemoMode(), demoCanSaveChangesLocally(),
and restoreOriginalDemoData(). Other minor cleanup.
Updated RootView.js to switch us back to loading config.json by using
"handleAs: 'json'" instead of handleAs: 'json-comment-optional'.
Updated config.json to un-comment-out the content.
Changed RootView.js so that if you're in demo mode, then in the UI, at
the top of the page, there's now a datastore status bar that (a) warns
you that changes aren't saved, and that either (b) invites you to
install Google Gears or (c) allows you to restore the original file data.
Minor change to base_style.css to change the color of the edit_tool bars
from light yellow to light blue.