Move completer construction to PGCli.__init__ and make refresh_completions a method of PGCli
Move completer construction to PGCli.__init__ and make refresh_completions a method of PGCli

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