Add README file in synced directory.

(So ‘vagrant up empty’ won’t need a mkdir)
README improvements

* More info on the different VMs
* Troubleshooting section
* Other, minor improvements
Work-in-progress on omniwallet install scripts

* Move over omniwallet install scripts from install-msc repo
* Minor changes to integrate with updated Vagrantfile and 
  directory structure.
Add pip install requirements, fixed user name replace