Merge pull request #1623 from lmorchard/773522-wiki-expiration-rebuild

bug 773522: Fix djcelery tables with a local migration
Make search span column on mobile, easier to use.
Merge pull request #1642 from darkwing/mobile-search

Make search span column on mobile, easier to use.
bug 926316: Add content extraction tools for new search indexes
bug 926316: Add extractors and new search indexes to wiki document model
bug 926316: Further tweaks to search analyzers