Update gem dependencies

Gemfile.lock

@@ -7,12 +7,12 @@ GEM
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    backports (3.6.4)
+    backports (3.6.6)
     better_errors (2.1.1)
       coderay (>= 1.0.0)
       erubis (>= 2.6.6)
       rack (>= 0.9.0)
-    browser (0.8.0)
+    browser (0.9.1)
     coderay (1.1.0)
     coffee-script (2.4.1)
       coffee-script-source
@@ -52,7 +52,7 @@ GEM
       rack (>= 1.0)
     rake (10.4.2)
     rr (1.1.2)
-    sass (3.4.15)
+    sass (3.4.16)
     sinatra (1.4.6)
       rack (~> 1.4)
       rack-protection (~> 1.4)