Add quality spec from vcr/bundler
user
```ruby
# coding: utf-8
# from https://github.com/vcr/vcr/blob/master/spec/quality_spec.rb
# from https://raw.githubusercontent.com/bundler/bundler/master/spec/quality_spec.rb
require "spec_helper"

if defined?(Encoding) && Encoding.default_external != "UTF-8"
  Encoding.default_external = "UTF-8"
end

describe "The library itself" do

  def check_for_spec_defs_with_single_quotes(filename)
    failing_lines = []

    File.readlines(filename).each_with_index do |line,number|
      failing_lines << number + 1 if line =~ /^ *(describe|it|context) {1}'{1}/
    end

    unless failing_lines.empty?
      "#{filename} uses inconsistent single quotes on lines #{failing_lines.join(', ')}"
    end
  end

  def check_for_tab_characters(filename)
    failing_lines = []
    File.readlines(filename).each_with_index do |line,number|
      failing_lines << number + 1 if line =~ /\t/
    end

    unless failing_lines.empty?
      "#{filename} has tab characters on lines #{failing_lines.join(', ')}"
    end
  end

  def check_for_extra_spaces(filename)
    failing_lines = []
    File.readlines(filename).each_with_index do |line,number|
      next if line =~ /^\s+#.*\s+\n$/
      failing_lines << number + 1 if line =~ /\s+\n$/
    end

    unless failing_lines.empty?
      "#{filename} has spaces on the EOL on lines #{failing_lines.join(', ')}"
    end
  end

  RSpec::Matchers.define :be_well_formed do
    failure_message_for_should do |actual|
      actual.join("\n")
    end

    match do |actual|
      actual.empty?
    end
  end

  it "has no malformed whitespace" do
    exempt = /\.gitmodules|\.marshal|fixtures|vendor|ssl_certs|LICENSE|etc/
    error_messages = []
    Dir.chdir(File.expand_path("../..", __FILE__)) do
      `git ls-files -z`.split("\x0").each do |filename|
        next if filename =~ exempt
        error_messages << check_for_tab_characters(filename)
        error_messages << check_for_extra_spaces(filename)
      end
    end
    expect(error_messages.compact).to be_well_formed
  end

  it "uses double-quotes consistently in specs" do
    included = /spec/
    error_messages = []
    Dir.chdir(File.expand_path("../", __FILE__)) do
      `git ls-files -z`.split("\x0").each do |filename|
        next unless filename =~ included
        error_messages << check_for_spec_defs_with_single_quotes(filename)
      end
    end
    error_messages.compact.each do |error_message|
      warn error_message
    end
    # TODO: fail build once this spec emits no warnings
    # expect(error_messages.compact).to be_well_formed
  end

end
```
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