Change development database to postgres
Merge branch 'master' into install_pg_for_development
This is necessary because I kept branching off of the other branches, instead of master. Hopefully this doesn't mess anything up.
Create an example database.yml file and ignore the real one.
Merge branch 'master' into install_pg_for_development

* master:
Remove comments in .gitignore
Merge pull request #35 from PhillyHealthDataRepo/install_pg_for_development

Install pg for development