Fix some rubocop reported issues

Gemfile

@@ -2,7 +2,7 @@ source 'https://rubygems.org'
 
 gemspec
 
-gem 'mutant', :path => '.'
+gem 'mutant',   path: '.'
 
-gem 'devtools', :git => 'https://github.com/rom-rb/devtools.git'
-eval(File.read(File.join(File.dirname(__FILE__),'Gemfile.devtools')))
+gem 'devtools', git: 'https://github.com/rom-rb/devtools.git'
+eval(File.read(File.join(File.dirname(__FILE__), 'Gemfile.devtools')))

spec/spec_helper.rb

@@ -24,7 +24,7 @@ RSpec.configure do |config|
   config.include(CompressHelper)
   config.include(ParserHelper)
   config.include(Mutant::NodeHelpers)
-  config.mock_with :rspec do |config|
-    config.syntax = [:expect, :should]
+  config.mock_with :rspec do |rspec|
+    rspec.syntax = [:expect, :should]
   end
 end

test_app/spec/shared/mutator_behavior.rb

@@ -30,7 +30,10 @@ shared_examples_for 'a mutator' do
 
       unless subject == expected_mutations
         message = "Missing mutations: %s\nUnexpected mutations: %s" %
-         [expected_mutations - subject, subject - expected_mutations ].map(&:to_a).map(&:inspect)
+        [
+           expected_mutations - subject,
+           subject - expected_mutations
+        ].map(&:to_a).map(&:inspect)
         fail message
       end
     end

test_app/spec/spec_helper.rb

@@ -6,4 +6,6 @@ require 'test_app'
 require 'rspec'
 
 # require spec support files and shared behavior
-Dir[File.expand_path('../{support,shared}/**/*.rb', __FILE__)].each { |f| require f }
+Dir[File.expand_path('../{support,shared}/**/*.rb', __FILE__)].each do |file|
+  require file
+end

test_app/spec/unit/test_app/literal/string_spec.rb

@@ -1,6 +1,6 @@
 require 'spec_helper'
 
-describe TestApp::Literal,'#string' do
+describe TestApp::Literal, '#string' do
   subject { object.string }
 
   let(:object) { described_class.new }