Fix gutter spacing on campaign pages

At the moment, the spacing in the gutters of campaign pages pull the 
page too far towards the left on desktop. On mobile, the padding is too
much. In both cases, the edges of the campaign page do not line up with 
the GOV.UK logo and search box in the header.

This fixes the padding based on values used for quick answers and 
guides.
Merge pull request #706 from alphagov/fix-campaign-spacing

Fix gutter spacing on campaign pages
Remove minutes to complete

The fields aren’t being used and can be accommodated by the recent
“need to know” field.
Merge pull request #707 from alphagov/remove-mins-to-complete

Remove minutes to complete
Remove Big Energy Saving Week text

It's hard to find out when Big Energy Saving Week is. It may have
started on the [27th January 2014][1], or [20th October 2014][2],
or both. And it looks like 2015/16 [hasn't been announced yet][3].

None of those are in December, so remove this text from the
homepage.

[1]: https://www.gov.uk/government/news/big-energy-saving-week-2014
[2]: http://www.citizensadvice.org.uk/index/campaigns/current_campaigns/besw.htm
[3]: http://www.citizensadvice.org.uk/index/campaigns/current_campaigns/besw/bigenergysavingweek.htm
Merge pull request #708 from alphagov/remove-big-energy-saving-week

Remove Big Energy Saving Week text
Show groups in search results

This is the frontend half of some work to group search results by facets
such as topics, mainstream browse pages, or organisations.  It will have
no visible effect without corresponding changes in rummager, so is safe
to merge and deploy before the rummager changes are made.

After this change, Rummager can suggest groupings of search results in
the search responses.  These are represented by a result document with
an extra member, "examples", containing a list of example items in the
group.

Rummager may also provide a suggested filter to apply to the search to
show all the items in the group.