Cvmfs extra repos

[pigay]

Allows users to configure extra CVMFS repositories and domains through CVMFS_EXTRA_REPOSITORIES and CVMFS_EXTRA_DOMAINS variables.

It also factorizes the configuration code for existing repositories.

An example for France Grilles repository:

variable CVMFS_EXTRA_REPOSITORIES ?= nlist('francegrilles.in2p3.fr',
                                           nlist('server_urls', nlist('CC-IN2P3', 'http://cccrnvmfss1li01.in2p3.fr/cvmfs/francegrilles.in2p3.fr'),
                                           'pubkeys_file', 'cvmfs/keys/francegrilles.in2p3.fr.pub'
                                           ),
                                     );

@Pansanel: This PR is far better than your #71 ;)

@jouvin: You are right, ncm-metaconfig should be better, in deed. I'll try to have a look at it soon (hopefully).

[Pansanel]

@pigay: it is a good refactory. Can you rebase on my previous PR and include metaconfig changes?

[pigay]

Do you mean I need to include francegrilles.in2p3.fr specific configuration (including public key) in the template-library? I had the feeling that this library should be restricted to general purpose code (which also applies to the other domains data such as desy and gridpp and maybe cern too, by the way). These details should fit better in another library (template-library-grid for example), don't you think?

Note: I don't have any metaconfig code yet...

[jouvin]

@pigay cvmfs is in the template-library-standard and everything related should be there. You are right that we may want to find a way to describe repo servers in a more generic way to avoid adding code for adding repo. In the meantime, this modification is acceptable for me as changing it should not affect the site configuration (the use of the new code is triggered by the name of the repos used at site which is independent of the configuration itself). I open #73 to track this.