--Changed the logig proceedure to store users credentials on the local disk when they sign up or sign in
Merge branch 'develop' of https://github.com/ehis/SmartShop into develop

Conflicts:
	src/main/java/com/mobile/smartshop/MainActivity.java
	src/main/java/com/mobile/smartshop/SignInActivity.java
	src/main/java/com/mobile/smartshop/SignUpActivity.java
	src/main/java/com/mobile/smartshop/User.java
-- re-added some changes to fix the merge