Updated openstack/openstack
Project: openstack-dev/devstack  58f8f429c88f11f6c2dc361306d920cece2f67ae

enable multiple collector workers

currently, a single worker thread writes received samples into
database. this is fine for most occasions but during message
spikes, it is not enough. this patch increase amount of workers to
half the number of processors (so we can ensure ceilometer maintains
lightweight design)

this will also help validate mulitple worker setup works.

Partial-Bug: #1336755
Change-Id: I33037f2f9ebfda43238e5cd0cff75adbed65d055