[tm4c gpio interrupts] add ability to define include files included in all files compilation.
[tm4c gpio interrupts] include tivaware.h using ADDITIONAL_INCLUDES mechanism
[tm4c gpio interrupts] add stellarisware.h which will serve is a place for common abstractions implementation on stellaris platforms
[tm4c gpio interrupts] consolidate tivaware.h and stellarisware.h
[tm4c gpio interrupts] use abstraction for gpio interrupt functions (changed names on the move from stellarisware to tivaware)
[tm4c gpio interrupts] include bsp gpio.c as some functions are not present in ROM
[tm4c gpio interrupts] enable gpio interrupts for tm4c123g