Prevent users from using obvious passwords

[bkthomps]

As recommended by NIST, disallow some or all of the following:

• Passwords obtained from previous breach corpuses.
• Dictionary words.
• Repetitive or sequential characters (e.g. ‘aaaaaa’, ‘1234abcd’).
• Context-specific words, such as the name of the service, the username, and derivatives thereof. (we already compare to username, but not to the name of the service)

[bkthomps]

Done.