Ensure authorization header problem decoded and encoded

Several layers of bytes <-> unicode to be danced about.
experiment with monkey patch for decoded response from httplib2

a requestU method returns content decoded from utf-8 to unicode.

Once fully used should clean up lots of duplicated decode() calls.
Correct handling of encoding mismatch in POST

Posted form handling is a bit confused between the two versions
of Python because parse_qs returns differently.

This solution (in web/query.py) is mapped to making the tests
pass but it may not be sufficient for all calling situations.
Time will tell.

POST problems discovered while making challenger tests work.