Modified Half Adder
Removed GATES inheritance from HalfAdder
HalfAdder Modified, Test cases added for HalfAdder
Modified FullAdder Class, Removing base class GATES
Added Test cases for FullAdder
Reordering the outputs to [CARRY, SUM]
Functions renamed as per the convention
HalfSubtractor modified
Removed BCD Adder
Merge pull request #231 from salil93/develop

HalfAdder Modified