oo-diagnostics: fail more accurately w/ districts required

bug 1077608
https://bugzilla.redhat.com/show_bug.cgi?id=1077608

With districts required for application creation, oo-diagnostics
now reports an error (not just a warning) if no district is created.
Also adjusted some of the other messaging around districts.
Merge pull request #4989 from sosiouxme/oo-diagnostics

Merged by openshift-bot