[Gluster-infra] Add gluster-nagios* to github

[Kaushal M]

Hi Sahina,

The gluster-nagios project currently lives in the 3 repositories in
review.gluster.org. Finding these projects on gerrit is not easy.

To be more visible it would be better if it is added to github under
the gluster organization. We can help set gerrit up to replicate to
the github repo. This will help with visibility of the project a lot.

~kaushal