Fix login if Hydra runs behind HTTP proxy with sub-path location

Dependencies

• [2] 3RMTP4QN Make /api/push-github public for private Hydra instances. This makes it possible to use webhooks to trigger evaluations for private Hydra instances.
• [3] E6S4CVUT Handle Referer not having a trailing slash
• [4] V7UDCU3W Fix a couple of encoding issues
• [5] 2P35LNRY Add XSRF protection for POST requests
• [*] J5UVLXOK * Start of a basic Catalyst web interface.

Change contents

• replacement in src/lib/Hydra/Controller/Root.pm at line 79
  [2.127]→[3.107:205](∅→∅),[3.107]→[3.107:205](∅→∅)
  − my $referer = $c->req->header('Origin');

  − $referer //= $c->req->header('Referer');
  [2.127]

  [3.205]
  + my $referer = $c->req->header('Referer');

  + $referer //= $c->req->header('Origin');