Update schema requirements

update access_provider match : permit is allowed (see man)
update ldap_access_filter : we can write a custom access_filter (see man)
Hi, 
I don't find any 'ldap_account_expire_policy' related field in the schema.
If I add it, will the component handle a new key ?
Sorry if you didn't meant that.
I'll fork and create a new branch so it will be easier to merge this.