model cleaning
Merge branch 'M6' of https://github.com/CS2340/BankNote into M5

Conflicts:
	src/JUnit/FileIOTest.java
	src/com/example/banknote/model/RegisterHandler.java
Merge branch 'M6' of https://github.com/CS2340/BankNote into M6
Merge branch 'M7_temp' of https://github.com/CS2340/BankNote into M7_temp