Remove the bookmarks 10 tags display limit/bug

Simply change the bookmarks tags display limit from 10 (original default value) to -1 
This change allows the bookmarks app to load all the tags you ever created, rather than just display the 10 first ones.
Seems to solve issue https://github.com/owncloud/bookmarks/issues/62 which has existed for long and could be problematic when you have more than 10 tags ;)