"""
merging the defaulacl and the pageacl
ruleset(only one rule for a group or a user in the acl) : e.g. : UserOrGroup:write,read
acl : e.g. : User1:write,read Group2:write,read,admin
a) When a ruleset is only setted in the pageacl,
nothing is changed for this user/group
b) When a ruleset is only setted in the defaultacl,
the whole acl rule for that user/group is appended to the pageacl
c) When a ruleset is setted in the pageacl with +rulset or -rulset and also given in the defaultacl,
the rulset of the defaultacl is appended to the end of the pageacl
d) When a ruleset is setted in the pageacl with not +/-rulset and also given in the defaultacl
the rulset of the pageacl and the defaultacl is merged to one rulset
and replacing the old ruleset in the pageacl
c) When a ruleset is setted in the pageacl with +/-rulset and not +/-rulset and is also given in the defaultacl
the ruleset which is not a +/-rulset is merged like d)
"""