fix(profiles): Move FEATURES into profiles.

Move all obviously safe features into the coreos profiles to further
reduce the magic in make.conf, leave the more fast-and-loose options in
make.conf to keep them kinda "special".
fix(profiles): Enable ccache by default.

This is such a huge win for repeated glibc and kernel compiles. :)
Merge pull request #234 from marineam/ccache

Enable ccache