Remove tab search JavaScript

- Tracking is only needed on unified
- Tabs don't exist so aren't needed
Remove non-unified search controller

Removes the controller and any methods, tests and templates which it needed.
Refactor/tidy government result presenter

Remove unused methods which were used by the tabbed templates and
simplify the logic of the methods which are still needed for the unified
search.
Update styles to only style unified search

Remove non-unified specific styles and merge the unified styles into the
styles so there is only one style block.
Remove route and forgotten presenter
Rename unified search to just search

Now that there is no non-unified search rename all the unified search
things to be just search.
Merge pull request #601 from alphagov/remove-non-unified-search

Remove non-unified search and rename unified search to search