Upgrade Rubocop to the latest version

.rubocop.yml

@@ -143,7 +143,11 @@ Style/TrailingCommaInArguments:
   Enabled: false
   StyleGuide: http://relaxed.ruby.style/#styletrailingcommainarguments
 
-Style/TrailingCommaInLiteral:
+Style/TrailingCommaInArrayLiteral:
+  Enabled: false
+  StyleGuide: http://relaxed.ruby.style/#styletrailingcommainliteral
+
+Style/TrailingCommaInHashLiteral:
   Enabled: false
   StyleGuide: http://relaxed.ruby.style/#styletrailingcommainliteral
 

Gemfile.lock

@@ -184,7 +184,7 @@ GEM
     angularjs-file-upload-rails (1.1.6)
     angularjs-rails (1.5.5)
     arel (3.0.3)
-    ast (2.3.0)
+    ast (2.4.0)
     atomic (1.1.99)
     awesome_nested_set (2.1.5)
       activerecord (>= 3.0.0)
@@ -512,8 +512,8 @@ GEM
     parallel (1.11.2)
     parallel_tests (2.14.1)
       parallel
-    parser (2.4.0.0)
-      ast (~> 2.2)
+    parser (2.5.1.0)
+      ast (~> 2.4.0)
     paypal-sdk-core (0.2.10)
       multi_json (~> 1.0)
       xml-simple
@@ -565,8 +565,7 @@ GEM
       rake (>= 0.8.7)
       rdoc (~> 3.4)
       thor (>= 0.14.6, < 2.0)
-    rainbow (2.2.2)
-      rake
+    rainbow (3.0.0)
     raindrops (0.13.0)
     rake (10.5.0)
     ransack (0.7.2)
@@ -620,11 +619,11 @@ GEM
     rspec-retry (0.5.6)
       rspec-core (> 3.3, < 3.8)
     rspec-support (3.7.0)
-    rubocop (0.49.1)
+    rubocop (0.55.0)
       parallel (~> 1.10)
-      parser (>= 2.3.3.1, < 3.0)
+      parser (>= 2.5)
       powerpack (~> 0.1)
-      rainbow (>= 1.99.1, < 3.0)
+      rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (~> 1.0, >= 1.0.1)
     ruby-progressbar (1.8.1)
@@ -670,7 +669,7 @@ GEM
     uglifier (2.7.1)
       execjs (>= 0.3.0)
       json (>= 1.8.0)
-    unicode-display_width (1.3.0)
+    unicode-display_width (1.3.2)
     unicorn (4.9.0)
       kgio (~> 2.6)
       rack