Maintenance: Load minimum possible css / reorg css

The key change this makes is it stops loading unused
css for non javascript users. All of css is loaded via javascript as needed

* Move css specific to Special:MobileMenu into its own css file
* Put all essential css for non-javascript users into ui.css and hamburger.css
t(for the left menu)
Load all javascript dependant css in javascript

* Define mobile.styles.page and put all styles that are not relevant to special pages
there
* Combine less statements for readability

Change-Id: I39d2ced37dde5e6bd2488870918dca2f7600ca6c