Prevent http errors during tests

[jayvdb]

gertty currently causes log

ERROR    https_everywhere.adapter:adapter.py:124 handle_error requests.exceptions.ConnectTimeout: HTTPSConnectionPool(host='ttygroup.org', port=443): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<urllib3.connection.VerifiedHTTPSConnection object at 0x7fb191ddc580>, 'Connection to ttygroup.org timed out. (connect timeout=15)'))
ERROR    https_everywhere.adapter:adapter.py:124 handle_error requests.exceptions.ConnectTimeout: HTTPSConnectionPool(host='ttygroup.org', port=443): Max retries exceeded with url: / (Caused by ConnectTimeoutError(<urllib3.connection.VerifiedHTTPSConnection object at 0x7fb191ddc580>, 'Connection to ttygroup.org timed out. (connect timeout=15)'))

While it is useful for the library to be able to skip past those problems, the tests should highlight them so they can be raised upstream.

Another more critical one would be TooManyRedirects.

[jayvdb]

b90799c was a too-many-redirects workaround - these should also be shown during tests.