Update changelog.
Update changelog.

eibanez/PyMySQL,mosquito/Tornado-MySQL,pymysql/pymysql,MartinThoma/PyMySQL,jwjohns/PyMySQL,DashaChuk/PyMySQL,yeyinzhu3211/PyMySQL,modulexcite/PyMySQL,xjzhou/PyMySQL,NunoEdgarGub1/PyMySQL,PyMySQL/PyMySQL,yeyinzhu3211/PyMySQL,eibanez/PyMySQL,boneyao/PyMySQL,anson-tang/PyMySQL,xjzhou/PyMySQL,jheld/PyMySQL,nju520/PyMySQL,aio-libs/aiomysql,lzedl/PyMySQL,wraziens/PyMySQL,Ting-y/PyMySQL,pulsar314/Tornado-MySQL,lzedl/PyMySQL,wraziens/PyMySQL,methane/PyMySQL,Geoion/Tornado-MySQL,PyMySQL/Tornado-MySQL