Bugfix: use apparent_encoding if encoding is set to None

[maiiku]

Defeat value for encoding attribute in class requests.Response is None. If server doesn't set it to something useful (ie on 202 responses) it remains None and gets passed to decode() and thus fails. Class requests. Response has very nice fallback, apparent_encoding, that is provided by the chardet library and can come in handy here.

[coveralls]

Coverage remained the same at 92.06% when pulling 8099166 on maiiku:bugfix_use_apparent_encoding_when_none_provided into 949056d on jkeyes:master.

[coveralls]

Coverage remained the same at 92.06% when pulling 8099166 on maiiku:bugfix_use_apparent_encoding_when_none_provided into 949056d on jkeyes:master.

[coveralls]

Coverage decreased (-0.03%) to 92.03% when pulling 110eb49 on maiiku:bugfix_use_apparent_encoding_when_none_provided into 949056d on jkeyes:master.

[coveralls]

Coverage remained the same at 92.06% when pulling 1b0f1d6 on maiiku:bugfix_use_apparent_encoding_when_none_provided into 949056d on jkeyes:master.

[maiiku]

I pulled in #88 into this PR as well
Also #90 does similar changes

[coveralls]

Coverage remained the same at 92.06% when pulling 964444b on maiiku:bugfix_use_apparent_encoding_when_none_provided into 949056d on jkeyes:master.

[jkeyes]

Thanks @maiiku, I'll take a look at this today.

[jkeyes]

Fixed and now in version 2.0, available from PyPi. See 8ca7d74 and f911a5f for the changes and tests.

Thanks again, I've added your profile to the AUTHORS page.