Handle non-zero exit code from git diff

The check for a changed repo in setup_develop() 'git diff --exit-code'
returns a status of 1 when the repo has changes; trap that so errexit
does not abort the script.

Bug-Id: 1285780
Change-Id: Ic97e68348f46245b271567893b447fcedbd7bd6e
Preinstall yum-utils; move sudo check before install

Some cloud images don't have yum-utils installed, so the call to
yum-config-manager fails.  Pre-install it (I still think it's easier
than fiddling config files).

Also, these repo setup steps are using sudo, but the root/sudo checks
happen after this.  Move them up before we start trying to do
repo/package installs.

Change-Id: I875e1f0663c9badc00278b2cc1a3b04ca3dde9fc
Merge "Handle non-zero exit code from git diff"
Add use_syslog to Marconi config

This patch adds use_syslog option to the marconi config file. This
is needed to allow marconi to run, when USE_SCREEN is set to False
in devstack.

Change-Id: I547697ec2745975e235a4e58cde81132ac37b70d
Merge "Preinstall yum-utils; move sudo check before install"
Merge "Add use_syslog to Marconi config"
Merge branch 'master' of https://github.com/openstack-dev/devstack