Player Instances Manager

* Player instances manager, to ease debugging (accessible from `__anm.player_manager`)
* Moved registering/providing/handling events code to `anm.js`

Usage:

    var player_manager = __anm.player_manager;
    player_manager.on(C.S_NEW_PLAYER, function(player) {
        // handling new player
    });
    player_manager.on(C.S_PLAYER_DETACH, function(player) {
        // handling detached player
    });
    var my_player_1 = player_manager.getPlayer('my-canvas-1');
    console.log(player_manager.hash);
    console.log(player_manager.instances);