Ports in new app form

* Add "ports" form field with a description about random ports
* Bold form errors to differentiate from help text
* Add description about comma-delimitedness of URIs form field

Addresses part of issue #124 

**Starting state:**
![screenshot 2014-04-28 13 11 43](https://cloud.githubusercontent.com/assets/29612/2822304/76db313e-cf11-11e3-9b69-ef456aacb752.png)

**Validation:**
![screenshot 2014-04-28 13 11 59](https://cloud.githubusercontent.com/assets/29612/2822308/7edb720e-cf11-11e3-8c13-b3db7a4dd826.png)