Initial work on the Mzalendo homepage redesign

This is a squash of many commits, to remove some confusion reversions -
originally many of these changes were made to the wrong files (the
common .scss files instead of the Kenya-specific .scss files) and later
commits removed those changes and added them back to Kenya-specific
files.  This made the history for the common files confusing, so all
this history has been squashed together now.

(All this work is by Zarino Zappia - the squashing and rebasing was done
by Mark Longair.)

The original commit messages are below for reference:

* slightly nicer staging message banner
* some automatic scss changes (mostly whitespace removal)
* lighter green header, non-italic tagline
* new search box in header - still feels a bit fussy
* search box improvements
* simpler nav bar
* dropdown arrows on dropdowny nav items; improved scaling for narrow screens
* darker footer to match header; cleaned up breadcrumbs
* fix header alignment
* tidy up search box css
* first iteration of homepage (without hero image)
* mostly finished homepage sidebar
* styling for blog posts on homepage
* make hero links work
* slightly closer to pep-8
* new layout for kenyan people/place/organisation pages
* icons for sharing buttons, and other sidebar fixes
* put disqus comments into their own box on the new people/places/orgs page
* mobile styling for the new person/place/organisation page
* actually use the right breakpoint
* better spacing on 640-960px displays
* better homepage spacing on 640-960px displays
* remove cruft from person page
* better formatting of email and postal addresses in new person sidebar
* better float clearing, and side-by-side arrangement on person page
* list person’s current positions on profile page
* add icons to person detail section headers
* correct poorly named image files from last commit
* add placeholder hansard appearances to person detail page
* fix left-col / right-col styling for person experience page
* fix up presentation of new hansard entries
* fix css bugs in opera mini
* revert core/person_feature.html, and create a fork for kenya with the required changes
* revert twitter_widget.html, and create a fork for kenya with the required changes
* revert site_header_search.html, and create a fork for kenya with the required changes
* revert core _breadcrumb.scss, and create a fork for kenya with the required changes
* revert core _colours_default.scss, and create a fork for kenya with the required change
* revert core _header.scss, and create a fork for kenya with the required change
* revert changes to core _footer.scss
* reformat core _footer.scss for legibility, reduce specificity of some selectors
* move kenya footer styles out into their own file
* move body background colour into _kenya_overrides.scss
* move kenya homepage styles into their own sass file
* revert changes to core _page.scss and add required overrides to _kenya_overrides.scss; fix related padding issue on kenya homepage
* revert core _menu.scss; move kenyan menu styles in their own file
For Kenya, include Hansard appearances server side
Set the number of hansard entries to show in the context
Split a long line in pombola/kenya/urls.py
KE: don't require Javascript for the appearances page
image at top of mzalendo homepage
mzalendo menu bar changes
mzalendo: links for new menu bar items
fix "appearanes" typo on person_detail page
new wording and url for homepage "find" button
smaller font size for kenya homepage quote
Bump the STATIC_GENERATION_NUMBER
fix kenya homepage hero image size now the quote is smaller