Add user agent to YUSU calls.

This fixes the 403 issue as YUSU's Apache setup will now permit our
requests, *but* it seems that the YUSU API is returning empty members
lists, which may imply another problem.

The user-agent is literally just 'MyRadio'.  This may need to change.

Based on http://stackoverflow.com/questions/2107759
Remove curl code.

This is dead code anyway, due to the return preceding it, and an
attempt to switch to using it just caused timeouts.  The file_get_contents
code works and is shorter, so we might as well use it until it's
necessary to seek less nasty ways of doing it.
Merge pull request #7 from UniversityRadioYork/yusu-user-agent

Add user agent to YUSU calls.