GPII-947: Code optimization in signup page.
Modifying conditions in if statements.
Removing variables with global scope.
Splitting functions gpii.signupPanel.confirm,
gpii.signupPanel.checkUsernameAvailability and
gpii.signupPanel.checkPasswdStrength.
Adding functionallity in gpii.signupPanel.checkPasswdStrength function
to implement "Must include numbers and letters" condition.
Modifying gpii.signupPanel.termsCheck function.
Comments about the functions.