V0.5.1: [Fix] Bug fix

Fixed runtime errors. Fixed date format to return exact notation of ddMMyy for single day range (eg. 01-09)

Signed-off-by: Kenneth Ham <kenneth.ham@comp.nus.edu.sg>
V0.5.1: [updated] jUnit Test cases

Updated test cases with 60 - 80% test coverage

Signed-off-by: Kenneth Ham <kenneth.ham@comp.nus.edu.sg>