before 6.2.2, some minor tests
validate works
validate email
validate the length
email validate finish
elementry email check
fix the "same email address by click twice" problem
BY --> add index for email.
The index will increase the speed to find by some filed,
it will cost the database more spaces.
add new field for users
ok the has_secure_password
authentication is also implemented by has_secure_password
previous the length check is not implemented, so last commit maybe in fault state