Return CLIENT_ERRORs for quickstart creation failures

Take https://bugzilla.redhat.com/show_bug.cgi?id=964123 for example.
Previously when the user ran:

rhc app create app15 python --from-code git://github.com/openshift/django-example.git

They would see output like:

----------
Unable to complete the requested operation due to: Node execution failure
(invalid exit code from node).  If the problem persists please contact Red Hat
support..
Reference ID: 03248488950f956e2158de6963e7b4ef
----------

That is useless because the error is not logged to the platform logs nor is the
error message useful for the user.  The only place that had the log was
/tmp/initial-build.log inside the gear which has already been destroyed at this
point.

The failures for this quickstart and the others I tried were not OpenShift
errors but legitimate quickstart bugs that the user could fix.  This patch will
send the errors back to the client. eg,

Could not find mysql database.  Please run:
rhc cartridge add -a app1 -c mysql-5.1