Local AudioSprite JSON data object support

[jounii]

Tested with modified audio sprite phaser-examples example. If ok, modified example could be another PR

[jounii]

Similar usage as with textureatlas. Usage example:

    game.load.audiosprite('sfx', 'assets/audio/SoundEffects/fx_mixdown.ogg', null, {
        spritemap: {
            'alien death': {
                start: 1,
                end: 2,
                loop: false
            },
            'boss hit': {
                start: 3,
                end: 3.5,
                loop: false
            },
            'escape': {
                start: 4,
                end: 7.2,
                loop: false
            },
            'meow': {
                start: 8,
                end: 8.5,
                loop: false
            },
            'numkey': {
                start: 9,
                end: 9.1,
                loop: false
            },
            'ping': {
                start: 10,
                end: 11,
                loop: false
            },
            'death': {
                start: 12,
                end: 16.2,
                loop: false
            },
            'shot': {
                start: 17,
                end: 18,
                loop: false
            },
            'squit': {
                start: 19,
                end: 19.3,
                loop: false
            }
        }
    });

[photonstorm]

Thanks for this! I have implemented my own take on providing this feature which is now in dev, but thanks for the suggestion and example json.