ability to raise problem reports

before this change, report-a-problems were raised by the 'feedback' app
directly into Zendesk. This change allows the 'feedback' app to make
API POSTs for problem reports being submitted by the public, with the
'support' app then raising it with Zendesk
support unauthorised response in json
permit API user to create problem reports
problem report: pass the source through as a tag
report a problem: remove unused views
requests controller: error instead of errors in JSON response
Merge remote-tracking branch 'origin/report-a-problem'