Revision 1816795

Fixed: In 'updateOrderContactMech' service, A check should be added to call 
'removeOrderContactMech'.
(OFBIZ-9967)

In case, user don't create orderContactMech while creating an order and wish to 
create orderContactMech after the creation then, 'updateOrderContactMech' 
throws error of 'oldContactMechId' parameter missing in 'removeOrderContactMech'
 service.

Adds a 'if-not-empty' check for 'oldContactMechId' field i.e, if 
'oldContactMechId' is available then only 'removeOrderContactMech' service 
should be called in 'updateOrderContactMech' service.

Thanks: Sonal Patwari