Remove the blue border underneath the title

... because it's not a design pattern that's used in other publishing apps.

Before:

![image](https://cloud.githubusercontent.com/assets/23801/5128715/badffc1a-70d4-11e4-83e5-5b2c11ab4a2e.png)

After:

![image](https://cloud.githubusercontent.com/assets/23801/5128707/ae008a32-70d4-11e4-904d-db11de980333.png)

/cc @fofr 
[Yup](https://github.com/alphagov/maslow/blob/master/app/assets/stylesheets/needs/need.css.scss#L57)