Removed pg_hba.conf
Removed postgres_run provisioning script and postgres-specific lines from bootstrap
Removed SQLAlchemy and Flask-SQLAlchemy from requirements file
Defined settings module to hold application-wide constants
Updated requirements file
Updated provisioning scripts to install mongo from PPA
Removed health "app". Flask blueprints are not pluggable apps.
Added Flask-PyMongo to requirements
Redefined application.py with PyMongo goodness
Merge branch 'feat/convert-to-mongodb'