added method for unlocking audio context on mobile devices
added method for unlocking audio context on mobile devices

spayton/phaser,BeanSeed/phaser,photonstorm/phaser,englercj/phaser,mahill/phaser,TukekeSoft/phaser,spayton/phaser,rblopes/phaser,BeanSeed/phaser,TukekeSoft/phaser,photonstorm/phaser,TukekeSoft/phaser,mahill/phaser,pixelpicosean/phaser