Removed documents still show in topic models

[shepdl]

When you add and then remove a document, it will still be included in a topic model.

Steps to reproduce:

1. Add a few documents to the document import list
2. Remove some of them
3. Create a new topic model
4. Select the topic model in the list of topics models
5. Click the "Docs" tab

All the documents you added in step 1 will be listed