Create framework for checkout.py

[jacobrdavis]

Create and frame checkout.py, a script which performs automated tests of the hardware (GPS, IMU, + modem), confirms the configuration matches that specified by the user in the config file, and returns a summary/diagnostics report. This is meant to be run ahead of deployment or during bench testing.

• import the checkout modules (checkoutGPS.py, checkoutIMU, ...)
• run each checkout module
• keep track of checkout module errors
• confirm the settings reported by each module match those specified in the config file
• create a summary for the user which reports passes/fails/warnings