Fix equality and hash for BaseLDAPEntry

[adiroiban]

Equality is implemented as

    def __eq__(self, other):
        if not isinstance(other, BaseLDAPEntry):
            return NotImplemented
        if self.dn != other.dn:
            return 0

        my = self.keys()
        my.sort()
        its = other.keys()
        its.sort()
        if my != its:
            return 0
        for key in my:
            myAttr = self[key]
            itsAttr = other[key]
            if myAttr != itsAttr:
                return 0
        return 1

while hash as

    def __hash__(self):
        return hash(self.dn)

I think that this is wrong is it can lead to objects with same hash but which are not equal.

[adiroiban]

A bunch of tests to consider

    def testEquality(self):
        """
        They are equal as they have the same DN and same attributes and
        values.
        """

    def testHashEquality(self):
        """
        Objects which are equal have the same hash.
        """

    def testHashInequalityEquality(self):
        """
        Objects which are not equal have different hash,
        even if the have the same DN (but different attributes).
        """

    def testInequalityWithSameType(self):
        """
        Instances for different DN are not equal.
        """


    def testInequalityWithOtherTypes(self):
        """
        Instances are not equal to other types.
        """