loadbalancer: implement rabbitmq binding

Implement RabbitMQ binding with these options:
- disabled by default for backward compatibility
- '5672' is the port by default
- mode TCP with roundrobin balance
cloud::image::api: Set default filesystem_store_datadir

Fix nfs mount resource when using nfs backend for glance images

Signed-off-by: Dimitri Savineau <dimitri.savineau@enovance.com>
messaging: support HAproxy binding

As an option and disabled by default for backward compatibility, allow
to export a puppet resource to create HAproxy binding for RabbitMQ
service.
Also add an option to specify the RabbitMQ service TCP port.
Merge pull request #673 from dsavineau/glance-filesystem-store-datadir

cloud::image::api: Set default filesystem_store_datadir
Merge pull request #652 from enovance/rabbit-haproxy

RabbitMQ load-balancing support
Remove Glance cache

Our default backend is RBD, using the 'keystone+cachemanagement' is
extremely dangerous since it will result in images getting cached in the
controllers under /var/lib/glance/image-cache/ and will potentially lead to
a full system sooner or later. Moreover since we use RBD CoW clone there
is no point to cache anything. Everytime a virtual machine is booted
often, this image will go into the cache. Think about Windows 50GB big
images, now think about 10 of them :D.

Going further if we have to use another backend I won't recommend using
it. I only Swift as a suitable backend for this, but regarding some
recent effort on the Nova side (image direct url) to get the image
directly from the storage entity I don't think it's useful to have any
images cached anyways.

Signed-off-by: Sébastien Han <sebastien.han@enovance.com>
Merge pull request #674 from enovance/disable-glance-cache

Remove Glance cache