Ability to set a Start Date or End Date for Exchange Rates

[#1]

Description - Ability to set a Start Date or End Date for Exchange Rates (similar to the capability for Job Role). 

Why is this feature important to you - Because Exchange Rates change monthly by our Finance/Accounting team. 

How would you like the feature to work - It would work similarly to the functionality available to Job Role.

Current Behaviour - Only have the ability to set the rate with no control over the start or end date.