Inserting bibliography fails while using bookmarks (Plugin V2.0a1)

pesho

When I try to insert bibliografy while using bookmarks (plugin version 2.0a1) i get a long (too long to type) error message pointing to line 363 in Zotero.py

Steps to reproduce:
* Select 'Bookmarks' in the preferences dialog
* Type some text and insert citation
* Click on "Insert Bibliography"

Alternatively:
* Select 'Fields' in the preferences dialog
* Type some text and insert citation
* Click on "Insert Bibliography"
* open the preferences dialog and select "Bookmarks"