Add optional debugging logs to test_HTTPServer.py.
Change the requested pagename in CaptchaProtectedResourceTests unittests.
Add a mocked DummyBridge class to test_HTTPServer.py.

This is used to test that bridges are actually returned on
'bridges.html' results pages, and is missing all of the real class's
methods except for `getConfigLine()`. The latter method needs to be
mocked because is used in `HTTPServer.WebResourceBridges.render()` to
get the bridge line to display to a client.
 Add a mocked DummyIPBasedDistributor class to test_HTTPServer.py.

 A distributor is a required parameter to the
`HTTPServer.WebResourceBridges` class. This one merely creates N random
`DummyBridges`, where N is the number of bridges we're told to return to
the client.
Add class wrapper for requesthelper.DummyRequest to support redirects.
Use the class wrapper DummyRequest in unittests in test_HTTPServer.py.
Fix X-Forwarded-For unittests in CaptchaProtectedResourceTests.

Apparently, we can't do:

    request.setHeader('X-Forwarded-For', '1.1.1.1')

because then BridgeDB never finds the header. Instead, we must do:

    request.headers.update({'X-Forwarded-For': '1.1.1.1'})
Always expect a Deferred from ReCaptcha.checkSolution().

Currently, we `checkSolution()` will return a RecaptchaResponse if the
HTTP POST argument fields are blank. Otherwise, it returns a
deferred. This is bad. It means we have to do all kinds of checks to see
if we can add callbacks on the returned object. It should always return
a deferred which callbacks with a RecaptchaResponse, and so we should
test for that and fail if that is not what is happening.
Add unittests for HTTPServer.WebResourceBridges.