Bump underscore-rails to ~> 1.8.0

Addresses #2857

Gemfile

@@ -172,7 +172,7 @@ gem 'd3_rails', '~> 3.5.5'
 gem "cal-heatmap-rails", "~> 0.0.1"
 
 # underscore-rails
-gem "underscore-rails", "~> 1.4.4"
+gem "underscore-rails", "~> 1.8.0"
 
 # Sanitize user input
 gem "sanitize", '~> 2.0'

Gemfile.lock

@@ -769,7 +769,7 @@ GEM
     uglifier (2.7.2)
       execjs (>= 0.3.0)
       json (>= 1.8.0)
-    underscore-rails (1.4.4)
+    underscore-rails (1.8.3)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.1)
@@ -965,7 +965,7 @@ DEPENDENCIES
   tinder (~> 1.10.0)
   turbolinks (~> 2.5.0)
   uglifier (~> 2.7.2)
-  underscore-rails (~> 1.4.4)
+  underscore-rails (~> 1.8.0)
   unf (~> 0.1.4)
   unicorn (~> 4.8.2)
   unicorn-worker-killer (~> 0.4.2)