getConstraints method change and output improvement

[ikwattro]

Currently this is the output of the getConstraints method :

Array
(
    [0] => Array
        (
            [property_keys] => Array
                (
                    [0] => neogen_id
                )

            [label] => Person
            [type] => UNIQUENESS
        )

    [1] => Array
        (
            [property_keys] => Array
                (
                    [0] => neogen_id
                )

            [label] => Channel
            [type] => UNIQUENESS
        )
)

• The method will be renamed to getUniqueConstraints
• This should return a label => array('prop1','prop2') output
• This should be possible to pass a label | array of labels as args