Remove now useless noop function
(start|stop)Intervals -> (start|stop)Polling
Smarter polling

We don't regularly try to get the track & anymore but try to be smart and
detect track changes. If the track changes, we try to get the track information
and the artwork. This reduces the average CPU usage a lot (quick tests have
shown a reduction by at least 50%).

This includes also an automatic retry if getting the track or artwork failed.
Depend on the correct branch, current_track_id -> track_id
Changelog for smarter intervals
WIP: lookup album when clicking on album search result
Add tests for trackHasChanged behaviour
Add node_modules ito .gitignore, add 'Contributing' instructions to README
Get artwork when track has changed, not only when we got the track
Move retry method down
Change 'Update' command in README
Add Matti to contributors
Bump version to 0.0.4
Revert "Remove height cap."

This reverts commit f73d35fc9278fb6ffe1fe405e952a45ce24181b1.
Add height cap again.
Merge branch 'master' into search_function

Conflicts:
	public/style.css