Switch to C language so we can specify operating systems. We have to install ruby 2.1 via rvm because the ruby interpreter on travis ci crashes when running rake ci, however that same version of ruby works fine on my local machine. This work around adds about 6 Minutes to the build and should be replaced as soon as possible to speed up builds.
This solves the warnings from -Wredundant-decls when overriding the
OUTPUT function with a function declared in another header.
It's better this is the non-default option, since using it requires either
a declaration of the new function OR a preprocessor guard on declaring
UNITY_OUTPUT_CHAR (as in unity.c here), in every file using the function.
See Pull Request #185 for more.
