Fix unit tests for simplebridge

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Schema: a new package in simplebridge for managing the state schema.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
add DummySandbox to tests, remove nil checking from ep.configure

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Merge pull request #131 from erikh/schema

Schema