Add doc skeleton for load_synthdefs
Create OSC::Server with internal port:

* No need to use explicit port number for OSC server that comms with
  scsynth - as scsynth will just reply back to the sender of the incoming
  OSC messages.
* Not specifying port number reduces brittleness - one step further to
  allowing multiple versions of Sonic Pi execute simultaneously on the 
  same host
Remove arbitrary sleep wait on os x boot:

* Need to do something similar for RP - should improve boot time and
  reliability.