Formbrowse improve

Adds hints to form pattern validation ("no spaces allowed."): 
![screen shot 2014-03-17 at 5 54 04 pm](https://f.cloud.github.com/assets/108094/2442209/b3b212d0-ae1e-11e3-90dd-ef02498de618.png)

Highlights selectable file types in browser:
![screen shot 2014-03-17 at 5 55 00 pm](https://f.cloud.github.com/assets/108094/2442219/d09d1d54-ae1e-11e3-9907-3a41a5dba792.png)
![screen shot 2014-03-17 at 5 54 53 pm](https://f.cloud.github.com/assets/108094/2442220/d0a856ce-ae1e-11e3-88ab-83c754118a66.png)