mongodb configuration -- refactor

[jeremydouglass]

Mongodb config is for "localhost" and this appears throughout the code rather than in a configuration setting. In our container stack it needs to be "mongodb"

We should refactor the host setting to a configuration variable, and determine the easiest way to support both localhost anaconda development and docker deployment.

[jeremydouglass]

For a reference example of a more fully-featured custom mongodb setup for docker, see:

• https://github.com/washingtonpost/docker-mongodb

[jeremydouglass]

Currently this is handled by deploy-fix.sh being run by the Dockerfile to change

mongodb://localhost --> mongodb://mongo

Added in 5db5e71

[jeremydouglass]

I've just noticed that this was already documented in closed issue #8

...however I think that changing from search-and-replace to an actual configuration option should stay on our to-do list.