To solve the problem of "db type could not
be determined" on py34 we have to run first
the py34 env to, then, run py27.

This patch puts py34 first on the tox.ini list
of envs to avoid this problem to happen.
Closes-Bug: #1489059

Change-Id: I4f791dfa620eacdd76cd46f193e190071ab64b6c