test/behat/mahara_behat.sh: Script updates to work better with Jenkins

Namely, quit on error and do not force ansi output

Change-Id: Ic6eed4e012ec986600a8db09518be7f2c9b2ef86
Signed-off-by: Aaron Barnes <aaronb@catalyst.net.nz>
Merge "test/behat/mahara_behat.sh: Script updates to work better with Jenkins"