Improve MayImplement by defining a TypeDefinition for qualified name

Add a typedefinition for QualifiedTypeName that is a string that represents a qualified type name. Improve the definition of MayImplements to be of this type, rather than string.

https://tools.oasis-open.org/version-control/browse/wsvn/odata/trunk/4.01%20spec/vocabularies/Org.OData.Core.V1.xml?op=diff&rev=947