Clearer information about how a proposal has been updated.

I've also reduced the size of the update text, since if it is longer
it can take focus away from the proposal title, and that's not what
we want.
Added republishing functionality to proposals. Closes #13

Conflicts:
	app/helpers/application_helper.rb
Merge remote-tracking branch 'origin/master' into euruko2013

Conflicts:
	app/assets/stylesheets/proposals.scss
	app/helpers/application_helper.rb
	app/views/proposals/show.html.erb
	config/routes.rb
	test/integration/proposal_test.rb