Show password rules in interface

[Bibby]

Currently, we can define some password rules in password plugin, for example:

• Require the new password to be a certain length (password_minimum_length)
• Require the new password to contain a letter and punctuation character (password_require_nonalpha)

The problem is, user cannot see these restrictions BEFORE submitting new password. It's a good idea to show all password rules in interface so that user can know how to choose a new password.