Slice info structure returned from "create" has illegal values

[nbastin]

SLICE_EXPIRED must be a boolean and SLICE_DESCRIPTION must be text, according to the spec:

{'SLICE_CREATION': <DateTime '20150831T00:18:00' at 7f3ecdd3fe18>,
 'SLICE_DESCRIPTION': None,
 'SLICE_EXPIRATION': <DateTime '20150901T17:17:53' at 7f3ecdd3fdd0>,
 'SLICE_EXPIRED': None,
 'SLICE_NAME': 'chtest-2',
 'SLICE_PROJECT_URN': 'urn:publicid:IDN+ch.geni.net+project+vts-infra',
 'SLICE_UID': 'e003e2ee-70e9-4a4d-8dfa-0f60829996b8',
 'SLICE_URN': 'urn:publicid:IDN+ch.geni.net:vts-infra+slice+chtest-2',
 '_GENI_PROJECT_UID': '10c88fc8-9d57-4971-8820-5b14323557f5',
 '_GENI_SLICE_EMAIL': None,
 '_GENI_SLICE_OWNER': '8a447f06-8bd5-4f32-8fd6-1a3528e7fa37'}

[tcmitchell]

See also #397

[tcmitchell]

Projects suffer from the same problem. expired is None, description is None. Fix that too.