Different user's network followers tab throws JavaScript error

Uncaught Error: Rendering of template "followers-template" failed: ReferenceError: displayOptions is not defined 
The problem seems to be that `waitForSelector` isn't completely reliable in our environment for some reason. The following code, for example:

```
casper.waitForSelector('#network-widget .nav li a[href="#network-followers"]',
    verifyUserHasFollower(user1));
```

with the function defined as

```
var verifyUserHasFollower = function(user) {
    casper.click('#network-widget .nav li a[href="#network-followers"]');
    // ...
```

generates the following error:

```
FAIL Cannot dispatch mousedown event on nonexistent selector: #network-widget .nav li a[href="#network-followers"]
#    type: uncaughtError
```

Clearly that's nonsensical. If the selector didn't exist, then the function should never have been called in the first place. I don't know whether it's a bug in casperjs (well, it probably is a bug of some sort) or all the async loading that we do is confusing it, but I haven't found a reliable way to wait for selectors.