Fix QQ login issue if the redirect url with query parameters.

For example, the redirect url looks like below,

/account/oauth/qq?returnurl=previouspath

Following the documentation of Oauth 2.0 of QQ, the 'redirect_uri' should be encoded.

http://wiki.connect.qq.com/%E4%BD%BF%E7%94%A8authorization_code%E8%8E%B7%E5%8F%96access_token#Step1.EF.BC.9A.E8.8E.B7.E5.8F.96AuthorizationCode
修复qq验证出错时无法解析问题
raise error_description on error
fix syntax error
merge zxkane's pull request
Merge https://github.com/yuanxu/social-oauth into yuanxu-master
Version 0.3.3