Add R scripts to work with VizGrimoireR

All of them use the VizGrimoireR library that analyzes
databases from each of the data sources analyzed in the
OpenStack community: gits, mailing lists, launchpad
and gerrit.

Change-Id: I393441881d42d3d2f1be6a4d476a478337733d92
Update links in entry page

Change-Id: Ic8916ac3c7bac4aad358458b96125efb8bb05a92
Add releases and companies study

Change-Id: I7b85da3fd601fd9f625d77da839c9242016f01ad
Merge "Add R scripts to work with VizGrimoireR"
Merge "Add releases and companies study"