Remove the relationships tab from the UI.

All good things must come to an end.  The relationships tab is
consistently broken due to yum behaving poorly in a threaded context.

We'll try to revive it some day when we're on rhel7 with dnf.  (That
will require a rewrite of the YumConnector as a DnfConnector).
Merge pull request #84 from fedora-infra/feature/all-good-things

Remove the relationships tab from the UI.