Create lockdown test for tag cloud

The tag cloud appears to have 100% code coverage, but it turns out that
there are no assertions regarding this part of the code, it just runs
without raising any exceptions.

Run the lockdown test with `bundle exec rake test:lockdown`.

The lockdown test is an `approval` test, meaning that whatever you
previously approved is considered the correct result.

The first time you run the test there is no previously approved result,
so the test will fail.

To make it pass copy the `.lockdown/received.html` file to
`.lockdown/approved.html`. By doing this you _approve_ the current
output as being correct.

If you run `bundle exec rake test:lockdown` again, the test should pass.
Moved get_stats_tag to new class
Moved instance variable assignment for get_stats_tags from StatsConroller into TagCloud
Cleanup StatsController
Cleaning up and simplifying variables
Moved sql queries into private method and reduced bloat.
Pair down to one method to create two instance objects.
Cleanup tags partial and reduce number of variables in StatsController
Two instance vairables using the same partial.
Extract methods from compute
Moved calculations out of views and general cleanup.