Search filters put into left column for tablet and desktop views

- added divs to allow column floats
- CSS for columns
- CSS copied from Whitehall for styling
- image asset copied from Whitehall
Wording changes to search filter

worked with @AmyWhitney
fix scrolling behaviour on search filter

- when the department filter is used on search pages, the page no
longer jumps back to the top
- JS change by @edds
- dependancy on
https://github.com/alphagov/static/commit/5438b01d529e625118b19461f55d93
30becee683
Patch styling bug with search filter in non-js desktop view
Search: additional whitespace above filter submit button
Merge pull request #355 from alphagov/search-filter-fixes

Search filter fixes