Add `env` information to the README.
Add DB setup information to the README.
Add `ragtime`, a migration library.

- And write a migration for the `users` table.
Add a shell script that can generate ragtime migration files.

- Needs to be run from the root of the project
- Run with `bin/generate-migration some-migration-name`
Add migrations to create a relation for exercises.
Add migration to create rating sets

[tim/asif]
Add migration to create ratings

[tim/asif]
Replace a hardcoded `form` action to `/exercises/1/ratings`

[asif/tim]
Add comments to the calculation functions in the `rating-set` namespace.

- Also refactor the `normalized-rating-sets` function.
Refactor calculation functions in Rating.clj
Move all the docstrings below the arglists.
Refactor methods in the `rating_set` model.
Add the `reload` ring middleware.

- The app is reloaded every time a `*.clj` file is changed.
- Only in development.
- Refactor the code that picks middleware based on the environment.
Run the server only on port 3000.
Merge pull request #1 from nilenso/tim-and-asifs-first-day

Tim and Asif's first day