Add migration styles

* Default non-presence-validated string fields to empty string to avoid nil values
* Put timestamps at the top when creating a table for consistency
Force push rebased feature branches before merging
Add note about Hound automatically reviewing style
Prefer `==` to `is` in CoffeeScript

Given that we prefer things like `&&` to `and` in ruby and other
languages, it'd be nice to be consistent about this in CoffeeScript as
well. I also find code that uses `is`, `isnt`, `and`, and `or` to be
signficantly less readable.
Preliminary Haskell style guide and best practices