Intermediate commit
FUNCTIONALITY INCOMPLETE

1. changed code so that the first row of the tariff table does not go in empty.
2. Added placeholder functions for saving the tariff
3. Added function to convert json to tariff
Added
1. Range editor for weight range column.
2. RealNumberEditor for the zone pricing columns. This was necessary because the zone price is a composite field having actualcost, rateid and costfield attributes. Out of this only the actualcost attribute was open for editing.
3. NumericRangeFormatter
4. FieldValueExtractor
corrected syntax error