fix parameter type for runAllTests to match header

At least in Microchip XC8 compiler, void (*runAllTests)(void) is treated as a different type from void (*runAllTests)().

Fix the definition of UnityMain to match the declaration by making the runAllTests's (void) parameter list explicit.
Merge pull request #68 from toybuilder/master

fix parameter type for runAllTests to match header (Thanks toybuilder!)