Update weibo.py

把request_access_token()和refresh_token()中的重复代码提取到parse_access_token()。
Merge pull request #33 from smallcode/patch-1

refactor request_access_token and refresh_token
rename parse_access_token to _parse_access_token as a private function
add timeout=5
remove simplejson dependency
prepare for version 1.1.4
add snspy
fix some bugs of QQMixin