Work around invalid public key issue
Work around invalid public key issue

I've faced with inability of keystone to recognize a public key
inside of `~stack/.ssh/autorized_keys` file. This happened because
of puppet writing three-line comment stating it was generated
automatically. With this fix it works fine.

Changes, I've done:
- Move public key path into separate variable
- Write public key into tmp file and pass it to `nova keypair-add`

Change-Id: I827b7e1695f61ef2742137195866cb2deb4a390f

openstack-dev/devstack-vagrant,openstack-dev/devstack-vagrant