Freeze cmd2 library on python2
Freeze cmd2 library on python2

The cmd2-0.9.0 is python3-only. Let's freeze the cmd2<0.9.0 as
recommended in https://pypi.org/project/cmd2/ while allowing any newer version on python 3+.

Change-Id: I5e631603e162da1d93347f954c9bc1af3f69597c

stackforge/python-jenkins