removing {prod,stage}-log plays, no longer used

The log machines were abandoned long ago.
standard Stanford {app,prod} users; add halawa, amayalah

Our user lists were a mishmash, this standardizes them across major
machine types (app servers and workesrs).

On the jumpbox also add Sherif Halaway.  Alejandro was already
provisioned there, adding now as cleanup.
Merge pull request #772 from edx/sefk/edxwest-users-cleanup

edx-west: clean up users, remove two unused plays (*-log.yml)