remove unnecessary env PAGER

This is already set by oh-my-zsh to `less -R`. This also takes care of the
diff highlighting in git vs the escape symbols. Not sure if env LESS is still
necessary now.

zsh/zshenv

@@ -9,7 +9,6 @@
 
 ## don't close less when I am done reading
 export LESS='-eirMX'
-export PAGER=less
 
 ## csv login
 export CVSROOT=:pserver:weiyi@cvs:/usr/cvsroot