Update Rubocop to version 0.37.2

**Why**:
The current version used by Hound (0.37.0) contains a bug with the RedundantMerge cop that causes a false positive when calling `update` on ActiveRecord objects. See rubocop/rubocop#2781

**How**:
Update to 0.37.1 or higher, which fixes the issue.

Gemfile.lock

@@ -200,7 +200,7 @@ GEM
       omniauth (~> 1.2)
     paranoia (2.0.2)
       activerecord (~> 4.0)
-    parser (2.3.0.3)
+    parser (2.3.0.4)
       ast (~> 2.2)
     pg (0.17.1)
     phantomjs (1.9.8.0)
@@ -286,8 +286,8 @@ GEM
       rspec-mocks (~> 3.4.0)
       rspec-support (~> 3.4.0)
     rspec-support (3.4.1)
-    rubocop (0.37.0)
-      parser (>= 2.3.0.2, < 3.0)
+    rubocop (0.37.2)
+      parser (>= 2.3.0.4, < 3.0)
       powerpack (~> 0.1)
       rainbow (>= 1.99.1, < 3.0)
       ruby-progressbar (~> 1.7)