Link GitHub repo in gemspec.

So people can find code faster when browsing
https://rubygems.org/gems/exercism.
Use minitest 5! <3
Merge pull request #9 from splattael/use-minitest5

Use minitest 5! <3
Merge pull request #8 from splattael/gemspec-homepage-link

Link GitHub repo in gemspec.
Avoid noisy minitest conflict

Because minitest is included in the ruby standard library, it first
complains about all the things, and then, afterwards, finds the correct
minitest code in the gem path, and finally runs the tests successfully.

That can be avoided by telling the code to load the gem directly.
Bump version

This is to ensure that the link to the repository is readily available
to whoever installs the gem.