fixed print, except and imports
fixed iter and basestring related
fixed send_cmd/readline str/bytes situation and py2 long type difference
fixed pickle return value situation with _cmd_builder
fixed a bug related to auto. decoding unpickled data instead of only those with appropriate flag. added a few more tests
fixed a bug related to key length vs encoded key length, Py3 compatible tests
fixed forgotten u''
updated README to indicate py3 compatibility
Merge branch 'py3-compatible'