install-autotest-server.sh: Abort script if failed to install deps

We count on yum and apt-get in a working condition, so
the autotest dependencies can be installed. But sometimes
that won't hold true, and the install process needs to
be aborted right there. Add this check to the script.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
installation_support/autotest-install-packages-deps: return exist status code

So that other scripts can determine if the installation was successful or not.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
Merge pull request #749 from autotest/setup-fix

install-autotest-server.sh: Abort script if failed to install deps