Add note indicating maximum length below textareas (bug 1031596)

![screen shot 2014-06-30 at 12 01 17 pm](https://cloud.githubusercontent.com/assets/23885/3432784/75476f52-0078-11e4-8273-17a25cdb1651.png)
![screen shot 2014-06-30 at 12 01 12 pm](https://cloud.githubusercontent.com/assets/23885/3432785/75565882-0078-11e4-88c3-b294e6ec8eb4.png)