Before it was only possible to make an ERP5 cluster connect to a NEO cluster
that was instanciated separately, by passing "name" and "master_nodes"
connection parameters in "storage-dict".

For an internal NEO DB, "name" and "master_nodes" is filled automatically
and you must instead pass a "server" dict, with same parameters as in NEO SR.
Currently, a NEO cluster name must be given. Later, we hope to generate a good
name automatically.

All this was implemented by refactoring NEO & ERP5 SR, with common files.
For the ERP5 SR, the root partition also serves as "root" partition for NEO
partitions: in other words, there's no second empty partition.

Dropped commit 971d0bb7
("erp5: Make possible extent the list of initial business templates to install").

Conflicts:
	stack/erp5/buildout.cfg
	stack/erp5/instance-erp5-cluster.cfg.in
	stack/erp5/instance-erp5-single.cfg.in
	stack/erp5/instance.cfg.in

erp5-cluster: haproxy, move generic configuration into default section

 Those signatures are old and unused anymore.

apache-frontend: Slave with cache now have dedicated virtualhost, add checkProxyCertificate, Strip Via header option

Reviewed-by: TrustMe

This description is required when requesting more than one zope partition
sharing a given IP (ex: webrunner-type setup).

The old address is no more:

    $ wget http://www.complang.org/ragel/ragel-6.8.tar.gz
    --2015-06-12 12:22:55--  http://www.complang.org/ragel/ragel-6.8.tar.gz
    Resolving www.complang.org (www.complang.org)... 192.155.89.46
    Connecting to www.complang.org (www.complang.org)|192.155.89.46|:80... connected.
    HTTP request sent, awaiting response... 404 Not Found
    2015-06-12 12:22:55 ERROR 404: Not Found.

because Ragel project moved to http://www.colm.net/open-source/ragel/

Adjust the download url properly.

/cc @cedric.leninivin
/reviewed-by: TrustMe