Merge branch 'master' into develop
Fix ReCaptchaProtectedResource.checkSolution() to pull response from deferred.

 * FIXES a bug introduced in #11127 where checkSolution() was expecting the
   boolean response from the reCaptcha API server, not a deferred as is now
   returned.
Merge branch 'fix/11218-deferred-solution-isvalid' into develop
Only use `t.w.client.HTTPConnectionPool` if available.

 * CHANGES bridgedb.txrecaptcha to create agents using the HTTPConnectionPool,
   only if our Twisted version is high enough.
 * FIXES #11219.
Merge branch 'fix/11219-httpconnpool' into develop
Update bridgedb.conf with changes from bridgedb-admin.git repo.
Add CHANGELOG entry for 0.1.6.
Add a real docstring to EmailServer.replyToMail().
Tweak the log message strings in EmailServer.replyToMail().
PEP8 whitespace fixes for EmailServer.replyToMail().
Fix class and __init__ docstrings for EmailBasedDistributor.
Make webserver Tor logo link to torproject.org.
Add link to CHANGELOG from webserver.
Change Contact link on webserver to go to support desk.
Move HTTPServer.geoipdb to _geoipdb and outside try function.

 * If it's outside the try function, it's easier to change from other modules
   (as well as for unittests).
Fix typo in inline comment in HTTPServer.
Rearrange logging calls during pygeoip import in HTTPServer.py.
Start writing unittests for the bridgedb.HTTPServer module.

The ReCaptchaProtectedResourceTests.test_render_POST_* unittests expose
the bug in #11231.
Fix CaptchaProtectedResourceTests.test_render_GET_noCaptcha unittest.

We shouldn't return ``(None, None)`` in a stub method when all the other
methods and child classes expect ``(str, str)``.
Update documentation for CaptchaProtectedResource.getCaptchaImage().