Get build cost estimates

Get build cost estimates

Generate and archive files containing cost, time & job info. If this is
a Openstack job call 'lftools openstack stack cost' to retrieve and
include costs from the stack members. Added two new scripts:
openstack-stack-delete.sh & job-cost.sh. The 'openstack-stack-delete
script' will retrieve the costs for the stack and delete the stack. The
'job-cost' will generate the job cost file which will include the costs
for the build agent and any Openstack members.

Issue: RELENG-1867
Change-Id: I658f5b42f90a28010e6f98f2f3c3ebb166192c30
Signed-off-by: Tim Johnson <tijohnson@linuxfoundation.org>