Instead of fprintf, C extension should use a Ruby logger

[rtyler]

Right now hermann_lib.c has a number of calls to fprintf to record information/logging info to stderr. It really should send that information to a Ruby logger.

[rtyler]

I think this should be fairly straightforward to accomplish if the constructor receives Ruby logger object

VALUE logger;

/* get the :debug symbol for dispatch */
ID debug_sym = rb_intern("debug");

/* dispatch to logger#debug with "LOGGING!" as the String */
VALUE result = rb_funcall(logger, debug_sym, 1, rb_str_new2("LOGGING!"));