Add configuration options

[BigBigDoudou]

GemsBond.configure do |config|
  config.github_token = ENV["TOKEN"]

  # formats to output
  exports = %i[html csv yml]

  # data to output, helps to focus on needed data and reduce spying time
  data = %i[
    contributors_count days_since_last_commit days_since_last_version
    downloads_count forks_count last_commit_date last_version
    last_version_date open_issues_count source_code_uri stars_count versions
  ]

  # if true, scores are calculated
  scores = true
end

So it is simple to make a very light configuration in order to focus on essential, for example:

GemsBond.configure do |config|
  config.github_token = ENV["TOKEN"]

  exports = [:csv]
  data    = [:days_since_last_commit, :days_since_last_version]
  scores  = false
end