Don't store channel objects in `user.channels`

Only store the name of the channel in the `user.channels` array as that is all that's necessary for figuring out common channels between users.
Attempt to cut down on the memory leaks
Revert `track by $index` in lines.html and userlist.html
Upgrading to AngularJS 1.2.15
Fix bug where user couldn't navigate to channel tabs

Hashtags in channel names were preventing the user from opening channel tabs as they were redirected back to the login page.
This change encodes hashtags prefixing the channel name in the URL.
Merge pull request #74 from coldstorm/performance

Performance improvements