sets up a Raphael canvas in the div element below here (the div has an id =canvas_container)
creates an object with a given identifier, tetrimino, and uses the "path" method to draw out a
a tetris shape
uses the objects "attr" method to syle it with gradien stroke colour, stroke-width,
stroke-linejoin (set to "round"), and a rotation of 90 degrees for its starting orientation
Finally it uses the shape's animate metod to rotate it 360 degrees over 2000 milliseconds
and with an "animation easing" of "bounce" to end up with the bouncyness.