Update cutest version.
Update gemspec.

* Add license information.
* Use git to list gem files.
Add makefile.

* Remove rake dependency.
Merge pull request #39 from frodsan/makefile

Add makefile.
Merge pull request #37 from frodsan/update_cutest_version

Update cutest version.
Merge pull request #38 from frodsan/gemspec

Update gemspec.