Bugfix: bugfix: disable on non-MFP tabs

Fixes minor bug where extension would stay enabled on a tab if URL changed due to search results, or if it was a newly-opened tab.

Disable on irrelevant sites

Changed name to MySurplusPal (was My Surplus Pal)
Button is now disabled & grayed out when active tab is pointed at sites that are not MyFitnessPal.

Initial release

Now available in the Chrome Web Store.