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
Moved start() inside init
HalfSubtractor modified
Removed BCD Adder
Merge pull request #231 from salil93/develop

HalfAdder Modified
shell banner modified
README Updated
Doc link updated
Merge pull request #234 from salil93/develop

Shell Banner Modified
fixes to base.py
Fixes to combinational.py
Merge pull request #235 from debugger22/misc

Miscellaneous fixes based on landscape.io
Merge branch 'develop' of https://github.com/BinPy/BinPy into connector_re-implementation