Start of p-button.

Added if statement at start of main while loop to check if p-button
flag was set. If so, closes fdDataOut, opens a new one, and clears
p-button event.
So...started implementing push button data file creation.

Not much here yet...simple if statement at start of main loop that
checks flag to create new data out file. Nothing is controlling this
flag yet...that will be the job of the push button. Currently working
on device tree overlay to set gpio0_30 to mode 7 with internal pull-down
enabled.