Use plural helper names.
Save some lines.
Show menu only if logged in.
Merge branch 'master' into bootstrap3

Conflicts:
	app/assets/stylesheets/application.css.scss
Navbar styled with bootstrap3.
Replaced .span6 by .col-md-6 and created icon helper.
Do not use whole width.
Fixed icon helper.
Repaired button styles.
Flash messages style.
Changed page headers according to bootstrap3.
Classic pagination style.
Repaired modals in versions#index.