serve wof with the right mimetype
new app "config" object, move "dev" setting there
cherry pick fix for ivaynberg/select2#581

ivaynberg/select2@c135db876ec9a620c8525a032ffa6be2f2d23159
numerous code and ux fixes and improvements

- move sanity into a property of modelSrvc
- actually send users' bug reports along with the interaction for
  settingsLoadFailure and sanity modals
- pass errbacks when using promise.then(...)
- offer refresh option in sanity
- use "close" instead of "continue" in modal buttons after setupComplete
- show error message in UI when updating proxiedSites fails
- offer restart option in sanity modal
- add tabindexes with appropriate values on all modals
- only set tabindexes on the visible modal