Move credits functions into a separate trait.

At this stage this is mainly to cut down the size of
MyURY_Metadata_Common, as well as increase cohesion.
Initial push of quotes stuff to make the links work for further testing.
Merge branch 'master' of github.com:UniversityRadioYork/MyRadio

Conflicts:
	src/Classes/ServiceAPI/MyRadio_Metadata_Common.php
	src/Classes/ServiceAPI/MyRadio_Season.php
	src/Controllers/Charts/doEditChartRelease.php
Rename MyURY_Creditable.
Rename MyURY_MetadataSubject.
Rename MyURY_Quote.
Factor out canRequestTrack?.
Factor out trackCanBePlayed and userCanMakeRequests.
Separate metadata and credits methods again.
How did getMeta end up in Creditable?
Update to current user API.
Implement requestFileAndLog.
Add config knobs for ITones request cap.
Implement can-make-requests check.
Break up query functions a bit.
Fix typos and split userCanMakeRequests further.
Privatise like Maggie Thatcher.
Missed some publics that should be private.
Convert requesttrackfrm to JSON.
Implement remaining requests counter.