Don’t consider actual files inside document bundles.

In this example option 2 should have been omitted.

```
~/C/C/trunk.cocoapods.org [master] » pod try LMAlertView
Updating spec repositories

Trying LMAlertView
1: LMAlertViewDemo.xcodeproj
2: LMAlertViewDemo.xcodeproj/project.xcworkspace
3: LMAlertViewDemo.xcworkspace
Which project would you like to open [1-3]?
```