combine all scripts (including jQuery which we now ship locally) into
one minified script using grunt-concat and grunt-uglify (fixes #155).

The scripts are concatenated in order (so they don't break) into
xbmc-video-server.js, which is then uglified into
xbmc-video-server.min.js.
ignore the unminified concatenated script
modify wol-poll.js so that the polling is started manually