add user type, and also add user login service.
add user registration and login function.
move test to test folder.
add exception in login service and exception mapper.
update login response json schema.
update userLoginResponse, only return the userName.
add find financial records by user function.
update response json field name
throw exception if user name is already exist when register.
add budget trail to record down the user's budget changes.
add exception handling
add DateSerializer to serialize date in BudgetTrail.
Update README.md
update budgetTrail key and userRecord key, add prefix.