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.
new tag cloud model helper and updates to stats controller
iteration 3 changes
iteration 4
first iteration 5 commit
second iteration 5 commit
interation 6

my favorite iteration so far
iteration 7
iteration 8
iteration 9
iteration 10
Merge pull request #1 from rrevi/iteration10

Iteration10