Fix issues, add CIE XYBri support, add Initial PHPUnit tests and Travis support.

[matthewbaggett]

No description provided.

[matthewbaggett]

Fix issues, add CIE XYBri support, add Initial PHPUnit tests and Travis support.

[DeannaGelbart]

getDistanceLabFrom() is not a Euclidean distance since it uses abs() instead of squaring
https://en.wikipedia.org/wiki/Color_difference#CIE76

Once I make the change the result seems to match http://colormine.org/delta-e-calculator (I only checked one color pair in the calculator so I didn't test exhaustively).

Here is my fixed version

public function getEuclideanDistanceLab(Color $color1, Color $color2)
{
    $lab1 = $color1->toLabCie();
    $lab2 = $color2->toLabCie();

    $lDiff = ($lab2['l'] - $lab1['l'])*($lab2['l'] - $lab1['l']);
    $aDiff = ($lab2['a'] - $lab1['a'])*($lab2['a'] - $lab1['a']);
    $bDiff = ($lab2['b'] - $lab1['b'])*($lab2['b'] - $lab1['b']);

    $delta = sqrt($lDiff + $aDiff + $bDiff);

    return $delta;
}

I can submit a PR but I want to check first that this project is still active?