gcc 64-bit target
Update makefile

The `build` directory is not created when running make, which yields an error. 
fix missing #define when UNIT_EXCLUDE_FLOAT is used
report correct (zero-based) index in string array equality mismatch
added Gemfile
debugging build failure on ruby 1.8
debugging build failure on ruby 1.8
set test-unit constraint to try to get it to work with ruby 1.8