VMware ESXi, mixed VRS target architecture

What's new:

1. Added pre-deploy support for VMware. Tested on R4.0R6.1 and 4.0R7.
2. Added support for mixed VRS architectures. That is, you can have some VRSs deployed on Ubuntu and some on RedHat/CentOS all using a single build.yml file.
3. Enhanced support for Dockermon install.
4. Documentation enhancements, including examples and how-tos.
5. Several bug fixes and infrastructure upgrades, including enhanced OpenStack deployment support and Jenkins CI integration.
6. Tested with 3.2R8, 4.0R4, and 4.0R7