Fix easy_install command in readme.
Fix easy_install command in readme.

janusnic/pgcli,yx91490/pgcli,thedrow/pgcli,d33tah/pgcli,bitemyapp/pgcli,darikg/pgcli,MattOates/pgcli,stuartquin/pgcli,joewalnes/pgcli,suzukaze/pgcli,lk1ngaa7/pgcli,janusnic/pgcli,n-someya/pgcli,joewalnes/pgcli,MattOates/pgcli,johshoff/pgcli,darikg/pgcli,bitmonk/pgcli,w4ngyi/pgcli,yx91490/pgcli,nosun/pgcli,koljonen/pgcli,bitemyapp/pgcli,lk1ngaa7/pgcli,TamasNo1/pgcli,zhiyuanshi/pgcli,TamasNo1/pgcli,bitmonk/pgcli,n-someya/pgcli,thedrow/pgcli,zhiyuanshi/pgcli,w4ngyi/pgcli,nosun/pgcli,dbcli/pgcli,koljonen/pgcli,dbcli/vcli,dbcli/pgcli,j-bennet/pgcli,d33tah/pgcli,dbcli/vcli,j-bennet/pgcli,suzukaze/pgcli,johshoff/pgcli