Generate rack-test.gemspec from Thorfile adding license, updating homepage

[junaruga]

• Added license information in Thorfile. Right now the gemspec file has 2 license parts in the file.
  Also the license information would be better to be included in Thorfile. And the gemspec file should be generated from Thorfile by thor command.
  This fixes Explicitly set license to MIT in .gemspec #130
• Updated homepage in Thorfile.

I used Ruby 2.2.7 to use thor.
Because when I used Ruby 2.4, the strings part of the gemfile was generated as "foo".freeze.
That is hard to check the difference of last modified one.

Below is how to generate.

$ which ruby
/usr/local/ruby-2.2.7/bin/ruby

$ ruby -v
ruby 2.2.7p470 (2017-03-28 revision 58193) [x86_64-linux]

$ which bundle
/usr/local/ruby-2.2.7/bin/bundle

$ bundle -v
Bundler version 1.14.6

$ bundle install --path vendor/bundle

$ bundle exec thor :gemspec
Wrote gemspec to rack-test.gemspec
WARNING:  open-ended dependency on rack (>= 1.0) is not recommended
  if rack is semantically versioned, use:
    add_runtime_dependency 'rack', '~> 1.0'
WARNING:  See http://guides.rubygems.org/specification-reference/ for help

[perlun]

Looks OK to me.

Again, this is an area I think it would be fine to change. I have never encountered a gem before where the gemspec is maintained via a Thorfile. It feels unnatural to me. The gemspec is more a file that you maintain manually, in my book, so I think we could move over to that pattern if you and/or @scepticulous agree. I don't really see the value of having it be machine-generated, when we could just as well let it be the "single source of truth" for its content instead.

[dennissivia]

I agree with @perlun about potentially removing thor from this equation. However I would actually merge this change the way it is, make the release.
Next we can discuss cleanup and removing things we no longer want/need.

[junaruga]

@perlun @scepticulous I agree with you guys.
I like maintaining the gemspec file manually. I like not using thor.

Next we can discuss cleanup and removing things we no longer want/need.

Yes, I agree the way.

[junaruga]

Thanks for the reviewing!

[voxik]

This line makes no sense. This is autogenerated by RubyGems for .gemspec files used after installation. Moreover, it is not visible on GH, but the separator is null character, not sure what separator is used here ...

[junaruga]

@voxik thank you for mentioning it. Yes, this PR includes the gemspec file generated from Thorfile by thor. The line will be removed by PR: #181 .

[junaruga]

I ran thor command on Ruby 2.2.7 when I generated the gemspec file. The Ruby's RubyGems was used to append the line. Maybe.
Because when I tried it on Ruby 2.4, freeze string was appended in the gemspec file. and there was so much difference between before and after modification. I did not like the difference.