Store bug ID to bugs DB when exporting
QA Reports base URL from config file

Generate the URL to reports on server side when performing DB queries to
get rid of hard-coded URLs in client widgets.

The reason for creating the URL in QA Dashboard instead of receiving it
from QA Reports was done mainly because of QA Reports exports single
reports when created/updated using an Observer and a model, neither of
which have access to url_for method if hostname is not provided.

We do anyway support only one QA Reports server so this will work just
fine for now at least.
Use Bugzilla service prefixes

QA Reports nowadays supports multiple Bugzilla services. Each service
has a unique prefix with which the correct service can be identified. It
also returns the bugs for each test case as a list of objects containing
ID, prefix, and URL from the endpoints from where QA Dashboard gets it's
data.

So, store the bugs with the prefix in place to the database (single
unique key still works). Then when fetching bug counts get other data
including the bug URL as well and not just the bug count. This way we
don't need hardcoded URLs or such.

This multi-Bugzilla approach now works for the QA Dashboard application.
Need to change Bugzilla exporter still to support multiple Bugzilla
servers.

It is also worth to notice that at this point old QA Reports
installations are not anymore compliant with QA Dashboard and vice
versa.