Merge pull request #19 from atlasapi/cassandra-configuration-update

Update atlas search to use new, more configurable cassandra code.
Switch to a memory-mapped file index for better performance
Merge pull request #20 from atlasapi/mbst-6874-use-memory-mapped-file

Switch to a memory-mapped file index for better performance
Index people

People are now indexed, and returned from the API if the type of person
is requested. The search endpoint has an additional key, contentIdentifiers,
which returns content identifiers for hits. The results key is now deprecated
but kept for backward-compatibility during the release
Merge branch 'mbst-7162-people-serach' into stage