Attempting to login with a blank password

As a person registering with their email address and password,
I should be required to enter a password of at least 8 characters.
to enhance the security of my account.

Need to
+ [ ] Require password field on Client (HTML)
+ [ ] Check for string length before running `checkpw`

Note: we will enhance this further with #66 in a future sprint.
For now we just need to prevent people from having a blank password (_or one with too few chars_).