support a generic calculation formatter when column.calculate is a proc
support a generic calculation formatter when column.calculate is a proc

asoltys/active_scaffold,silverpond/active_scaffold,ajacksified/active_scaffold,BookingBug/active_scaffold,ajacksified/active_scaffold,silverpond/active_scaffold,BookingBug/active_scaffold,silverpond/active_scaffold,BookingBug/active_scaffold,asoltys/active_scaffold