Sync with current core group

In the thread[1] the PTL removed 5 members of nova core.

The change makes nova.json match [2]

[1] http://lists.openstack.org/pipermail/openstack-dev/2014-December/052279.html
[2] https://review.openstack.org/#/admin/groups/25,members

Change-Id: I33bd7b713c3ab5bb62f4d4fc975809021731eeb0