Bug Fixes and Improvements

- changed all strings to use F() macro to conserve RAM
- moved some messages to new NRF_VERBOSE_DEBUG conditional to make debugging with NRF_DEBUG on more viable
- added display of details of any hardware error event inside debugEvent()
- fix a bug in handling 64 bit pipesOpen and pipesClosed members -- don't return AND masked pipesOpen value as an 8 bit integer or you can only use 8 pipes -- instead, compare result of the mask to 0, and return the boolean result
- be more deliberate in handling the 64 bit pipesOpen and pipesClosed masking to ensure compiler uses a 64 bit mask
- implement getDeviceVersion()