add psycopg2 to requirements
use explicit new PostgreSQL settings
make SQL PostgreSQL compliant, fix all tests
move salt configuration to PostgreSQL

- drop MySQL-python dependency from requirements/base.txt
- define port in coffeestats pillar
- rename environment variables in uwsgi configuration template and csdev.sh template
- replace mysql installation and configuration states with PostgreSQL states
- restart uwsgi/nginx on changes to database or application
switch TravisCI configuration to PostgreSQL
Finish move to PostgreSQL