Don't comment out the service_providers options

Disabling the neutron service providers was necessary during the
icehouse development cycle, but is not needed anymore.

Change-Id: I5a9a1632d34ab66e3e0192687e093f0ecbbf87d2
backport: icehouse
Closes-Bug: #1326856
(cherry picked from commit fbdc2f013eee1997c32171ab49193a2bb048a37c)
Merge "Don't comment out the service_providers options" into stable/icehouse