add more possibility for validation of password

[tburguie]

Add possibility to check for a certain number of lower, punctuation
characters and a number of rule to check among min_lower, min_upper,
min_digit, min_punct.

[coveralls]

Coverage remained the same at ?% when pulling 5b28b68 on tburguie:master into 245bafb on kakwa:master.

[kakwa]

Hummm,

the ppolicy simple is meant to be... simple, I think it would be a better feat for a more complex ppolicy module such as:

https://github.com/kakwa/ldapcherry-ppolicy-cracklib/blob/master/lcppolicy_cracklib/__init__.py

Also, setting default value might be a good idea:

self.get_param('min_point')

self.get_param('min_point', 0)

Otherwise it will introduce a breaking change in the configuration format.