Implements NOISSUE: Added units information to surface area

Sign-off: @mumia 

Created a directive to handle the units information (changes according to the city selected). Also renamed the label, depending if we want the room area or property area.

Screenshots:

![screen shot 2013-12-30 at 13 23 20](https://f.cloud.github.com/assets/74459/1822195/c4616de8-7155-11e3-82c3-cfbd86ef62c9.png)
![screen shot 2013-12-30 at 13 23 36](https://f.cloud.github.com/assets/74459/1822196/c46515a6-7155-11e3-8f8d-713b31580ca9.png)

![screen shot 2013-12-30 at 13 23 48](https://f.cloud.github.com/assets/74459/1822197/cb55ede0-7155-11e3-876f-e4b0f72a1986.png)