Issues/366 improve linkhelper

Fixes #366 and #367. 
Bug fixes and improvements for the link helper. 
Shows the form fields in landscape mode on the iPhone by hiding the title and description.
Updates keyboards to use Next and Done buttons. 
If URL title text is selected then the URL field has the cursor when the view appears. 

Bonus: The custom media size dialog gets the improvements for free. 

After shot:
![screen shot 2013-11-18 at 2 57 30 pm](https://f.cloud.github.com/assets/1435271/1566744/2e181292-5094-11e3-8a03-c60cf7427141.png)
![screen shot 2013-11-18 at 2 57 51 pm](https://f.cloud.github.com/assets/1435271/1566745/2e2826aa-5094-11e3-8712-3fe4f1975e06.png)