return only metadata related to static types and not dynamic ones

http://stackoverflow.com/questions/26400078/breeze-building-metadata-with-the-nhmetadatabuilder-when-using-envers

We had an issue using NHibernate Envers. Envers adds dynamic types mappings(_aud tables) and those mappings can't be used with breeze. The workaround is to get only mappings which have the Type property not null in EntityMetaModel.