New size checking task.

This task clones the test repository and the base repository and compares the sizes, if the former is more than 1.05 times the latter the task will return False.
tweaks to get the size checker working

* Corrected a few syntax problems
* Fix the size check to be recursive
* Use the size of the checked-out branch rather than the whole
  repo, because the latter is not time-invariant
* Reformatted HTML output slightly