Implement Lougout button w/ history deletion

	modified:   PayBack/res/layout/activity_contact.xml
	modified:   PayBack/res/layout/activity_main.xml
	modified:   PayBack/src/com/example/payback/MainActivity.java
	modified:   PayBack/src/com/example/payback/Transaction5Activity.java
Merge branch 'master' of https://github.com/milneti/PayBack