Set fading params when playing a sound

This sets the in and out fade lengths to either 20% the length of the
sound up to a maximum of 2.5 seconds.
Update Sound to bit shift volume

Before the sound was multiplying by a float, the bit shifting seems to
give a better sounding wave.
Update setGlobalVolume to use helper function for setting sound

The volume is now stored in terms of bits.  In order to be able to send
a percent float value the helper function needs to be called to
correctly set the volume internally.
Initialize push key controller