Fixing the taxon count by taking the trash out of the count

Fixes: LINNA-2104

The reason the count differed so much was because the webservice count did not take into account the trashed taxa (which are listed in a separate table).

Also improved the readability somewhat.

Functional test

Check out the acceptance site (user:sesam, pass:open nu)

• Look at the count in the stats block on the front page.
• Check the count in the taxon tree.

• See that they are the same.