Yarko/vagrant upfix

This fixes a recent vagrant pull merge to mirror development usage for native installations, that is usual workflow is

- git clone;
- create-dev-env.sh
- (work);
- git pull;
- (work);
- ...

(current master runs `scripts/create-dev-env.sh` on each VM bringup - which besides not being usual, has side effects: re-initialized CMS db's on osx host, re-installations, etc.).

scripts/vagrant-provisioning.sh:   changed to only create / initialize the workspace the first time.   Also, reported "up" IP address now reflects the VM's actual address.

README.md:  cleaned up previous notes, add info on how to create a clean VM; added section for django debug toolbar and admin access