Replace NvpPluginV2 with NsxPlugin

The king is dead, long live the king!

Partial-implements blueprint: nicira-plugin-renaming

Change-Id: I9b71479a8d4228d45a6591b169c489c0107fb04c
make ceilometer work if you don't enable ceilometer-api

when doing ceilometer in a multihost devstack, you don't want
ceilometer-api running on the computes. Under -o errexit this
became fatal.

Change-Id: Ie43c8724ba467b810f5a3b075dea45d66dde8648
only do a dbsync if on the database node

ceilometer should only try to reset the database if it's actually
on a node where there is a database.

Change-Id: Ibcfec0556829bff0938e3769c19d34ae6c02b738
Use glance image-show to check for uploaded Docker images

The behavior of the code being replaced was failing
with '-o errexit' should that, as in the common case,
the image has not been uploaded into Glance.

While we could workaround this using a '|| :', the existing
code also happened to overwrite the DOCKER_IMAGE global
which is used elsewhere. It seemed prudent to either change
this variable name or remove it altogether.

Finally, using 'glance image-show' is more deterministic
than grepping the output of 'glance image-list'.

Change-Id: I23188155966ae9db64259b4a9d25a0d98c63c912
Closes-Bug: 1286443
Merge "Use glance image-show to check for uploaded Docker images"
Merge "make ceilometer work if you don't enable ceilometer-api"
Merge "Replace NvpPluginV2 with NsxPlugin"
Merge "only do a dbsync if on the database node"
Merge branch 'master' of github.com:openstack-dev/devstack