MongoDB replicaset is now an option

In non-HA setup, we don't want MongoDB replicaset.
Let's put it as an option, enabled by default to keep backward
compatibility.
Merge pull request #648 from enovance/mongo-without-rs

MongoDB replicaset is now an option
N1KV VEM support to vSwitch

Bring n1kv_vem driver support to vSwitch configuration in Neutron
Compute & Network agent.

It use the n1kv_vem agent from puppet-neutron using default parameters
that could be replaced by custom datas.
Also add an unit test with a new context when running n1kv_vem agent.
Merge pull request #635 from enovance/n1kv-neutron

Cisco Support for Virtual Networking
Rakefile : Verify Puppetfile syntax

A :validate_puppetfile task has been added to Rakefile so it is possible
to detect Puppetfile syntax error before merging future pull-request
Merge pull request #649 from enovance/r10k_check

Rakefile : Verify Puppetfile syntax
Bring EMC VNX support for volumes backend

- Add a new backend to support EMC VNX direct driver
- Updating puppet-cinder refs to have the upstream commit with EMC
  support
- Unit test with a new context
- Update the README

Note: .fixtures and Puppetfile has been put on a dev branchi for cinder module to debug while the patch is upstream.
Allow using NFS shares for both Glance and Nova

Closes-bug #653
Merge pull request #654 from enovance/nfs-for-both-glance-and-nova

Allow using NFS shares for both Glance and Nova
Merge pull request #640 from enovance/emc_vnx

Bring EMC VNX support for volumes backend
NFS backend for Cinder volumes
Merge pull request #656 from enovance/nfs-volume-backend

NFS backend for Cinder volumes
N1KV support to Virtual Networking

Plugin Side: cloud::network
===========
- Add a flexibility to modify default ML2 plugin.
- Add non-ML2 Cisco plugin support.

Note: The configuration is for Cisco Nexus with
neutron.plugins.cisco.network_plugin.PluginV2 core plugin &
neutron.plugins.cisco.n1kv.n1kv_neutron_plugin.N1kvNeutronPluginV2
vswitch plugin.

Agent Side: cloud::network::vswitch
==========
- Bring n1kv_vem driver support to vSwitch configuration in Neutron
Compute & Network agent.
It use the n1kv_vem agent from puppet-neutron using default parameters
that could be replaced by custom datas.
- ensure nexus1000v package is installed
- Also add an unit test with a new context when running n1kv_vem agent.

Also update the README.