Support of Long primary keys.

[izhleba]

Key points
Table.scala:

def _primaryKey: Option[Field[Int, Int]]
TableGenerator.scala:

 val primaryKey: Option[InnerCol] = if (primaryKeyNames.nonEmpty) {
      val pkName = primaryKeyNames.head
      val pk = columns.find(_.rs.name == pkName).getOrElse(sys.error(s"Field for primary key not found in ${table.cat}.${table.name}"))
      if (pk.shortScalaType == "Int") Some(pk) else None
    } else None