added PosSystem class
changed BackEndMain to a static class
Update PosSystem.java
Merge branch 'master' into posSystem
Merge branch 'posSystem' of https://github.com/SpyMaster356/Assignment-2 into posSystem
Merge pull request #35 from SpyMaster356/posSystem

Pos system
Merge pull request #36 from SpyMaster356/master

update