Add alias so that pip cannot be used in favor of pipenv

To install pipenv do following:

    \pip install pipenv

shrc

@@ -313,6 +313,9 @@ __safe_alias py2=python2
 __safe_alias ipy=ipython
 __safe_alias ipy3=ipython3
 __safe_alias ipy2=ipython2
+__safe_alias pip="echo Use pipenv! 1>&2; false"
+__safe_alias pip2="echo Use pipenv! 1>&2; false"
+__safe_alias pip3="echo Use pipenv! 1>&2; false"
 __safe_alias rl=rlwrap
 __safe_alias igosh=gosh-rl
 # Sometimes SHELL cannot be used. For example, when running bash inside zsh