Implement Health Status view, fixes #306

Initial PR.

To follow up:
- list localizers with https://github.com/pascalchevrel/list_localizers (per repo/per year, and globally for the locale) And maybe globally for all locales
- Improve view performances (cache)
- Fix getStatsPaneDP test (currently disabled)
- Shall we remove code for http://transvision.mozfr.org/showrepos/ or both views should coexist?
- Last commit is most of the times from L10n Drivers, even on Desktop
- Shall we merge in the UI some of the components on Desktop?
- Prettify UI
I'm still finding this regex confusing. You want strings that don't start with $case, so you need the negative lookahead.

Let's say "$case" is 'browser/metro', you regexp is ```#^((?!browser/metro).)*$#```, while I think that ``` #^(?!browser/metro).*#```should be enough.