Removing unneed bluetooth code

+ By playing through AudioManager.STREAM_VOICE_CALL, routing audio to
bluetooth is handled properly for us.
+ This change removes the code that was preparing to manually play
the call waiting tone through bluetooth.
+ Small fix ups for javadoc

Bug: 26932998
Change-Id: Ib5f872c72cdfa44ab0bc2ff5d7e41645aba813ff