Create SimpleType for DisciplineActionLength

Two properties DisciplineAction.DisciplineActionLength and DisciplineAction.ActualDisciplineActionLength independently define themselves as xs:int, they should be modified to reference a single simple type. See also DATASTD-866 which talks about changing these properties from xs:integer to xs:int, and see also DATASTD-799 and DATASTD-801 which talk about a request to change this data type to xs:decimal. Consolidate to a simple type should happen no matter what the final underlying type ends up.