run rubocop as part of default CI tests

.rubocop.yml

@@ -0,0 +1,33 @@
+Metrics/BlockNesting:
+  Max: 2
+
+Metrics/LineLength:
+  AllowURI: true
+  Enabled: false
+
+Metrics/MethodLength:
+  CountComments: false
+  Max: 10
+
+Metrics/ParameterLists:
+  Max: 4
+  CountKeywordArgs: true
+
+Style/CollectionMethods:
+  PreferredMethods:
+    map:      'collect'
+    reduce:   'inject'
+    find:     'detect'
+    find_all: 'select'
+
+Style/Documentation:
+  Enabled: false
+
+Style/DoubleNegation:
+  Enabled: false
+
+Style/SpaceInsideHashLiteralBraces:
+  EnforcedStyle: no_space
+
+Style/TrailingComma:
+  EnforcedStyleForMultiline: 'comma'

Rakefile

@@ -1,5 +1,3 @@
-#!/usr/bin/env rake
-
 require 'bundler'
 Bundler::GemHelper.install_tasks
 
@@ -7,7 +5,11 @@ require 'rspec/core/rake_task'
 RSpec::Core::RakeTask.new(:spec)
 
 task test: :spec
-task default: :spec
+
+require 'rubocop/rake_task'
+RuboCop::RakeTask.new
 
 require 'yard'
 YARD::Rake::YardocTask.new
+
+task default: [:spec, :rubocop]