Move government colour to theme

* Partition theme into sections with comments
Split needs CSS into constituent parts

* Create files for form, revisions and need
* Break up pre-refactor
* Remove p.new-need which wasn't being used
Refactor need view markup and styles

* Generally avoid fighting against bootstrap with extra layers of
abstraction
* Move theme and variable imports into application, for inclusion
everywhere
* Improve margin helper classes to avoid specificity problems
* Improve semantics of header partial and alignment of button group
* Use bootstrap breadcrumb with added margin