Candidate code to solve issue #30

To show the total number of bookmarks market with some tags is related with the most expensive task that Getboo runs now. It was a good opportunity to review related code and use some tricks to make it run better.

Maybe it is not the most beautiful way to do it, but I decided to return together the total number of bookmarks, and the list of bookmarks to be shown in the same method call. This made possible to calculate both results with only one DB SELECT call.

With this change, when user is navigating in the results the system is responding faster. The code related to this functionality (and page) is really difficult to change. I'm giving priority to realize "faster" spotted refactoring then do radical changes.

Need your review @elizeu !