password complexity rules required

At the moment Sakai has no sort of limits on what constitute a valid password. It is therefore possibel to set a password that is 1 character long. There should be a mechanism for enforcing password complexity rules. One sugestion we have is that there be 3 levels setable in sakai.properties:

1) Enforce minimum leght n (default with a default n=5 or similar)
2) require numbers and characters
3) disctionary check