Updated multiple gems.

Gemfile.lock

@@ -131,7 +131,7 @@ GEM
       coffee-script-source
       execjs
     coffee-script-source (1.12.2)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.3)
     crass (1.0.4)
     debug_inspector (0.0.3)
     domain_name (0.5.20180417)
@@ -177,9 +177,9 @@ GEM
     netrc (0.11.0)
     nokogiri (1.8.5)
       mini_portile2 (~> 2.3.0)
-    nokogumbo (2.0.0)
+    nokogumbo (2.0.1)
       nokogiri (~> 1.8, >= 1.8.4)
-    rack (1.6.10)
+    rack (1.6.11)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails-deprecated_sanitizer (1.0.3)
@@ -206,12 +206,12 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    ruby-graphviz (1.2.3)
+    ruby-graphviz (1.2.4)
     sanitize (5.0.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.8.0)
       nokogumbo (~> 2.0)
-    sass (3.6.0)
+    sass (3.7.2)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -235,14 +235,14 @@ GEM
       net-ssh (>= 2.8.0)
     strip_attributes (1.8.0)
       activemodel (>= 3.0, < 6.0)
-    thor (0.20.0)
+    thor (0.20.3)
     thread_safe (0.3.6)
     tilt (2.0.8)
     totp (1.0.0)
       base32
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    uglifier (4.1.19)
+    uglifier (4.1.20)
       execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext
@@ -287,4 +287,4 @@ DEPENDENCIES
   webrick
 
 BUNDLED WITH
-   1.16.6
+   1.17.1