- clarify the purpose of "timezone", alleviate confusion in [ticket:2326]
- clarify the purpose of "timezone", alleviate confusion in [ticket:2326]

robin900/sqlalchemy,olemis/sqlalchemy,WinterNis/sqlalchemy,wfxiang08/sqlalchemy,Cito/sqlalchemy,Cito/sqlalchemy,elelianghh/sqlalchemy,bootandy/sqlalchemy,276361270/sqlalchemy,alex/sqlalchemy,Akrog/sqlalchemy,sandan/sqlalchemy,davidjb/sqlalchemy,EvaSDK/sqlalchemy,EvaSDK/sqlalchemy,inspirehep/sqlalchemy,elelianghh/sqlalchemy,dstufft/sqlalchemy,hsum/sqlalchemy,brianv0/sqlalchemy,hsum/sqlalchemy,davidfraser/sqlalchemy,monetate/sqlalchemy,itkovian/sqlalchemy,sandan/sqlalchemy,wfxiang08/sqlalchemy,276361270/sqlalchemy,inspirehep/sqlalchemy,Cito/sqlalchemy,alex/sqlalchemy,graingert/sqlalchemy,halfcrazy/sqlalchemy,itkovian/sqlalchemy,pdufour/sqlalchemy,sqlalchemy/sqlalchemy,pdufour/sqlalchemy,j5int/sqlalchemy,wujuguang/sqlalchemy,dstufft/sqlalchemy,alex/sqlalchemy,wujuguang/sqlalchemy,bdupharm/sqlalchemy,j5int/sqlalchemy,graingert/sqlalchemy,davidjb/sqlalchemy,halfcrazy/sqlalchemy,brianv0/sqlalchemy,ThiefMaster/sqlalchemy,WinterNis/sqlalchemy,monetate/sqlalchemy,bootandy/sqlalchemy,ThiefMaster/sqlalchemy,zzzeek/sqlalchemy,Akrog/sqlalchemy,epa/sqlalchemy,bdupharm/sqlalchemy,olemis/sqlalchemy,epa/sqlalchemy,davidfraser/sqlalchemy,robin900/sqlalchemy