Extracted translation strings from the views

This leaves the views pretty much as I found them, just with the strings extracted to the translations file.

I'd like a little bit of debate about this: I'm pretty happy with it, but it's not without problems, particularly around the need (real or not) to have different page titles and nav entries (i.e. Agenda / Chosen Proposals).

There are technical solutions to this (e.g. cascading translation, where the nav would pick a nav-specific title if there were one and fallback to the page title if not), but editorial solutions may be preferred.

If we're happy to proceed then there's a bunch of tidying for the calls to `t()` that could be done, as well as the clean up of views that comes next...

Accepting this would close #37