bugzilla: log error for problems without components
bugzilla: skip problems with no reports

This might happen when clustering is in progress.
bugzilla: pick report with highest count

When creating new ticket make sure we pick
report with highest count so we don't end up
linking to unrelated report if clustering
splits the problem.

Closes #172.
bugzilla: use bthash for linking to problems

It's better to use hashes instead of IDs which might change, we have
support for this since 3000b1b.

Closes #170.
hub: redirect /problems/ to /problems/hot/

Closes #145.
hub: reword new issue link to "Report a bug for the server"