First swing at adding memcache.
Merge branch 'master' into add_memcache

Conflicts:
	census_extractomatic/api.py
	census_extractomatic/config.py
	requirements.txt
Use memcache to cache geo tiles.
Add memcache to TIGER calls.
Install memcached as part of fabfile.
Add a cache flush command to fabfile.
Shorten up the deploy fabfile step.
Merge pull request #16 from censusreporter/add_memcache

Add memcache