Add date filtering facet
Remove all vertical padding on the top and bottom of filters

Going to add this to contained elements instead so elements stack inside grey boxes sensibly
Put vertical whitespace onto form elements
Remove one level of indentation

I'm trying to restructure the css a bit to make it easier to add new input types to it when required. This commit de-nests some of the SCSS to make it easier to read.
Take .filter, .radio-filter, .checkbox-filter and .text-filter out of .filter-form scoping.
Change comment to make it more understandable
remove superfluous 'px' from '0px'
fix indentation
Move some input styles out of desktop only
Correct label and placeholder
Add margin to top of checkbox-container
Refactor Radio Facet

This commit includes the work to move the sentence generation to the
individual radio facet.
Refactor Select Facet

This commit includes the work to move the sentence generation to the
individual select facet.
Refactor Result Set Presenter and Finder

With the new sentence generation by fragment,
finder#facet_sentence_fragments returns an array containing all the
fragments which is then joined together by result_set_presenter.
Also with the link to the Finder without that filter applied, we now
use the other_params portion of the sentence fragment.
Add Date Facet sentence fragment and spec

Also refactor the view to not break when there's no value present.
Merge pull request #79 from alphagov/date-filtering-facet

Date filtering facet