Add Python 2.6 test env in tox
Add Python 2.6 test env in tox

Luckyseal/wechatpy,cloverstd/wechatpy,wechatpy/wechatpy,mruse/wechatpy,cysnake4713/wechatpy,EaseCloud/wechatpy,Dufy/wechatpy,zaihui/wechatpy,Luckyseal/wechatpy,messense/wechatpy,jxtech/wechatpy,chenjiancan/wechatpy,navcat/wechatpy,zhaoqz/wechatpy,cysnake4713/wechatpy,cysnake4713/wechatpy,mruse/wechatpy,chenjiancan/wechatpy,Dufy/wechatpy,cloverstd/wechatpy,hunter007/wechatpy,hunter007/wechatpy,navcat/wechatpy,Luckyseal/wechatpy,zhaoqz/wechatpy,tdautc19841202/wechatpy,zaihui/wechatpy,tdautc19841202/wechatpy,EaseCloud/wechatpy,tdautc19841202/wechatpy