Remove use of Ansible

[Shillaker]

The Ansible scripts are now mostly obsolete. They are still used/ mentioned in a couple of places:

• MPI docs - these need to be updated, perhaps to point at the experiment-mpi repo instead.
• cpp-root Dockerfile - currently used to set up LLVM. We can instead transfer the commands to the Dockerfile and delete the LLVM playbooks.
• base Dockerfile - currently used to set up the runtime filesystem, we can also transfer the commands to the Dockerfile here and delete the playbook.
• Bare metal setup- we no longer support deploying on bare metal, so these docs and the link to them from the README can be deleted, along with the tasks in faasmcli.

Once this is done, a final grep for ansible and playbook should show up any more usage.