Make the program configurable to support one or two sensors

[danielknapp]

We recently changed main.cpp to work with 2 sensors connected to the BBB. It is not necessarily the case that we will have 2 sensors for each BBB. Making the code to be configurable either from a file or from passing an argument into the terminal. Passing an argument into the program when launching it on the terminal is preferable unless there are significantly more things we'd want configurable.

[gwong89]

done, needs to be tested on BBB