Remove width on legend

It shouldn't have been there and was breaking layout in ie6
Turn of js for scrolling-checkboxes for ie lte 7

These checkboxes perform better in ie lte 7 if you remove the js enhancements.
Make scrolly boxes always open in ie 6 and 7

As we have turned off JS for ie 6 and 7 also disable the closed state in the CSS.
This fixes a gnarly rendering bug in ie6 where the legend of a closed facet renders over the top of an opened one as reported in pivotal here: https://www.pivotaltracker.com/story/show/68536850
Hide toggle for facets that have toggling disabled

For IE 6 and 7 or where javascript is not enabled do not show the clickable open/close arrow as it doesn't do anything.
Use '0' instead of '0px'

Thanks @bradleywright!
Merge pull request #23 from alphagov/ie-6-layout-fix

Ie 6 layout fix