Insteon: Redesign Voice Command Creation

- Created get_voice_cmds routine which returns a hash of available voice commands for each device type.
- Moved all voice commands out of Insteon.pm into more appropriate classes
- Added some new unique device voice commands

This design is much more pleasurable to work with and much less confusing.  All prior voice commands were kept, although a few of them have been broken for a little while.

This fixes issue hollie/misterhouse#181