Suppress warnings when running "gem build marcel.gemspec"

[junaruga]

• Suppress warnings when running "gem build marcel.gemspec".
• Typo filenames => file names.

Right now there are warnings, running gem build marcel.gemspec.
I fixed the warnings.
I also changed a small typo "filenames" to "file names" to use words in dictionary.

$ gem build marcel.gemspec
WARNING:  open-ended dependency on minitest (>= 0, development) is not recommended
  if minitest is semantically versioned, use:
    add_development_dependency 'minitest', '~> 0'
WARNING:  pessimistic dependency on rack (~> 2.0.1, development) may be overly strict
  if rack is semantically versioned, use:
    add_development_dependency 'rack', '~> 2.0', '>= 2.0.1'
WARNING:  See http://guides.rubygems.org/specification-reference/ for help
  Successfully built RubyGem
  Name: marcel
  Version: 0.3.2
  File: marcel-0.3.2.gem

[junaruga]

I updated Gemfile.lock too. But do we really need to manage the file? Can we remove the file from the repository?

I think that managing the dependency packages and the version with only rubygem-marcel.spec and Gemfile might be better.

[georgeclaghorn]

Please leave this line alone. This change is not necessary to suppress gem build warnings.

[junaruga]

@georgeclaghorn ok rebased!

[junaruga]

Please leave this line alone. This change is not necessary to suppress gem build warnings.

Here is a PR to leave the line alone. #9