Added typedefs and a custom struct for some USB data used in some upcomming commits
Moved the main two cleanup lines for the usbInit() call into their own routine
Added calls to grab the Tiva C's USB descriptor blocks so that interface configuration is not hard-coded
Added 3 variables to store the endpoints to use in all IO calls in flashprog
Implemented validation and checks for the configuration interface returned in the interface association structure, and grabbed the control endpoint for the virtual serial port used by flashprog