Trunk-4444 Validate order overlap with scheduled date

Comments:
In Order.java:
          - getCalculatedStartDate and getCalculatedEndDate are kept public for future use.
          - Can rename getCalculatedEndDate and getCalculatedStartDate with better names (if any).
Why did you choose to add this concept to this file? This file is set up specifically for a certain test and assumes all drugs and drug_order are of the same concept but the data you are adding contradictory to it. You can either add another file or use an existing row in the test data set and tweak the dates within the same test method.