update uglifier to 4.2.0

Gemfile

@@ -46,7 +46,7 @@ gem "sidekiq-cron", "1.1.0"
 
 # Compression
 
-gem "uglifier", "4.1.20"
+gem "uglifier", "4.2.0"
 
 # Configuration
 

Gemfile.lock

@@ -742,7 +742,7 @@ GEM
       ethon (>= 0.9.0)
     tzinfo (1.2.6)
       thread_safe (~> 0.1)
-    uglifier (4.1.20)
+    uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext
@@ -923,7 +923,7 @@ DEPENDENCIES
   twitter (= 6.2.0)
   twitter-text (= 1.14.7)
   typhoeus (= 1.3.1)
-  uglifier (= 4.1.20)
+  uglifier (= 4.2.0)
   unicorn (= 5.5.3)
   unicorn-worker-killer (= 0.4.4)
   uuid (= 2.3.9)