How to install Fuel on vSphere

ref-arch -- add 7000-vcenter- -- add info about
how Fuel is run under vSphere

planning-guide -- add 7300-fuel-on-vsphere-prepare
which needs some information about how to plan for this

user-guide -- add 7350-fuel-on-vsphere.rst with instructions
for preparing the vCenter for the Fuel installation
and installing Fuel on vSphere

Change-Id: Ib6cc7f55e716459ce41a7826074aa25406fd64e2
Merge "How to install Fuel on vSphere"