Don't use system pip things in tox

We added features to tox to use venv python. Use them.

Change-Id: Id20633e7bfc473d7c01aecdd78fc687f65942699
Avoid matching ip -s netns exec in IpFilter

Simply avoid the occurence of "netns", "exec" anywhere
on the command line.

Change-Id: Ibce8ba87de7cf30abcf468df24ab7cf0adf061c5
Closes-Bug: #1081795
Merge "Don't use system pip things in tox"
Run py33 test env before others

Run the python 3 test environment before the others so
the python 3 version of anydbm used by testr picks a
file format known to the python 2 version of the library.

Change-Id: I4d94fa47fe0b4a0f815261f7048866cccab11299