Fix styling on registration form errors when creating new user

#### Story ####
- https://www.pivotaltracker.com/story/show/68394446

#### Note ####
- updated login styles to account for fields marked with error classes, based on Jeff's recommendations
- this also fixes a similar issue when updating user account info via the Account link on the dashboard view

#### Screenshot ####
- broken styling
  - ![screen shot 2014-03-27 at 3 41 22 pm](https://cloud.githubusercontent.com/assets/456952/2550785/051c9b3e-b687-11e3-92e2-e6b9b7254d84.png)
- fixed styling
  - ![screen shot 2014-03-28 at 10 40 33 am](https://cloud.githubusercontent.com/assets/456952/2550772/f11af0e0-b686-11e3-9e5d-d45345bcc0e2.png)