Widen enumeration PermissionAttributeSimpleType

[gcdev373]

Enumeration PermissionAttributeSimpleType may be Author, Owner, Read, Write, Execute.

Please add values Create, Update. Delete, Use

[at055612]

Update is probably synonymous with Write but I guess it makes sense to have enumerations that more closely match system's permission models.

[at055612]

Relates to #76