Revert "process doc changes using gevent"

This reverts commit 644b981c974c4b33c7203ef5a5b3a854eae4c95b.

The use of gevent seems to be causing more issues than its worth. Can't get it to run without this error:
```
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/home/simon/.virtualenvs/commcarehq/local/lib/python2.7/site-packages/socketpool/backend_thread.py", line 50, in run
    time.sleep(self.delay)
  File "/home/simon/.virtualenvs/commcarehq/local/lib/python2.7/site-packages/gevent/hub.py", line 79, in sleep
    switch_result = get_hub().switch()
  File "/home/simon/.virtualenvs/commcarehq/local/lib/python2.7/site-packages/gevent/hub.py", line 135, in get_hub
    raise NotImplementedError('gevent is only usable from a single thread')
NotImplementedError: gevent is only usable from a single thread
```