Adjust permissions

This changeset
- removes executable bits from README.md
- adds executable bits to shell scripts

These changes are largely symbolic, except for osbash.sh which users are
expected to run without having to change permissions or passing it as an
argument to bash.

Partial-Bug: 1312764
Implements: blueprint openstack-training-labs
Change-Id: I91cce85862171a360c31e1e7628a708dfefd70f1
Merge "Adjust permissions"