tower and smaccmpilot: good build for flight code with tower uarts

* still need to port the motor output driver into tower, it is
  nonfunctional at the moment
bump tower (forgot last commit)
bump submodules for the day and add new ivory-px4-hw package to the build

not a whole lot really accomplished today:
* started refactoring motors code, stubbed out ardrone driver implementation
* chased down a really silly dependency bug in tower
bump smaccmpilot and tower for day
tower api bumped, smaccmpilot mavlink performance improved
bump smaccmpilot
tower + smaccmpilot: finally a reliable UART driver in tower!