hub: fix component select form field style
hub: fix dajaxice staticfiles urls
hub: call backtrace diff js only when required
hub: rename reports.js - > problem.js
hub: query ReportArches with counts
hub: sort arch query
hub: reworked report/problem statistics

- number of rows is now limited to three
- it is possible to expand the table with '+N more' button
- no empty tables are rendered
- now using generic table for such metrics
bugzilla: handle download errors gracefully
add comments to faf-bugzilla-create-bugs
faf-create-problems: don't die on cross-opsys clusters

Now logs a warning stating that only one OpSys per cluster is supported.