Install memcache and use it to cache searches

Memcache servers and the cache expiration period can be configured in
the ini file.

Caching can be disabled from the API using nocache=True
Cache subject searches for longer
Change search result json format to avoid iteration in webview

In addition to author uuids in query.limits, results.items and
results.limits, include index of the author in results.auxiliary.authors
Merge pull request #233 from Connexions/search-result-json

Change search result json format to avoid iteration in webview
Merge pull request #232 from Connexions/cache-searches

Install memcache and use it to cache searches
Adjust format (pep8)
Label with format items of the search query.
Use common table expression when building the match set.
Add a +1 bonus to search results that are not derived.
Fix existing test to adjust for new null parentage weight boost.
update test for books first ordering