Merge pull request #44 from fidothe/mode_rulesets

Rework Modality to allow definition of modes in config/modes.rb
Extract translation strings for the dashboard index
extract dashboard title; fix typo; remove cruft
Extract translation strings for Proposals/index

Also refactor some shared strings from the dashboard into the proposal
translations
Extract translation strings from Proposals/show
Extract translations from Proposal/new
extract translation strings from Proposal/edit
Extract translation strings from RSS feeds
fix typo in call to t()

I thought I'd run the tests before the last commit but clearly I was
delusional.
Extract translation strings from Selections/index
Extract translation strings from User/show
Extract translation strings from User/edit
rationalise the translations strings a bit

The biggest change in approach here was pulling a clever one/many string
processing into a simple, stupid, choice between a one and a many
translation string. The cleverness made the translation string setup for
it pretty confusing
Fix html_safe issue and a typo
extract translation strings from layout
Isolate Vestibule-specific translation strings

Move them into config/locales/vestibule/*.yml