PR - [TA-3862] - Add documentation to all_pages param in campaign dashboard


![image](https://cloud.githubusercontent.com/assets/2509619/4351592/4963af12-420f-11e4-8576-c8ca22f3453f.png)

Just a minor wording suggestion:
Retrieve all pages including pages that are not active. It is _false_ by default, and therefore only active pages will be included in the results.