fix first time setup problems

* Some .env.sample keys were 'key: value' instead of 'key=value'
* Run only db:migrate -- db:schema:load then migrate throws an error:
  'relation "producers" already exists'. It re-runs the migrations from
  the start because the migration table is empty.

Running the migrations instead of db:schema:load means the migrations
table will be filled out for future migrations.
Merge pull request #24 from heroku/doug-fix-setup

Fix first time setup problems