Add checkbox for enabling/disabling extension and restyled popup form.
Change manifest to only include test servers.
Transition to using RequireJS for the majority of the file loading.

Now instead of specifying an index file that lists the individual JS
files, you just include a link to the file you'd like to be set as the
data-main attribute of the require.js injected into the game page.
Load content scripts at document_end and after checking for socket lib.

This is to prevent a conflict that was occurring when loading the files
prior to global-game and socket.io.