feat(olcne): deploy GlusterFS module and Heketi.

[hussam-qasem]

Signed-off-by: Hussam Qasem hqasem@tyeb.com

Fixes issue #423 :

• Create Vagrant SSH Key in PEM format to be used by Heketi
• Create SSH Known Hosts to enable Host Ket checking
• Enable ol8_appstream required by GlusterFS
• Modify Vagrantfile to provision EXTRA_DISK on Worker nodes only.
• If DEPLOY_GLUSTER=true :
  • Install GlusterFS server on Worker nodes.
  • Install Heketi on OPERATOR node using default values for port, admin-user, secret-key.
  • If NB_WORKERS is less than 3, patch the hyperconverged Kubernetes storageclass volumetype.
• Allow to configure host-only Subnet (my Virtualbox is stuck on 192.168.56.* and I cannot change it!)
• Update the README.md documentation accordingly.