Issue title: Unable to login using Android client and CAS plugin
 Issue body: Your Rocket.Chat version: 0.29
When trying to login via CAS using the Android app, the login page is correctly shown but after providing username and password a blank page is shown (see attached screenshot).

Everything works correctly when using a browser.
![cas_login_attempt](https://cloud.githubusercontent.com/assets/1647955/15181259/8485a598-1786-11e6-97eb-1b324f50ea45.png)

 Comments: 
 Comment 0: Does this only effect the mobile application or does this happen when doing mobile web also?
 Comment 1: The issue affects the mobile application only. No issues while using Chrome or Firefox for Android.
 Comment 2: Can confirm. I have the same issue.
 Comment 3: Pull request created. Anyone that can test, please do so!
 Comment 4: Updated to 0.33.0 and the CAS login works again, thank you!
{'source': 'GithubIssues', 'repo_name_with_owner': 'RocketChat/Rocket.Chat', 'issue_id': 154234072, 'repo_stars': 36672.0}