Update gem dependencies

Gemfile.lock

@@ -1,16 +1,17 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.1.4)
+    activesupport (4.1.5)
       i18n (~> 0.6, >= 0.6.9)
       json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
       thread_safe (~> 0.1)
       tzinfo (~> 1.1)
     backports (3.6.0)
-    better_errors (1.1.0)
+    better_errors (2.0.0)
       coderay (>= 1.0.0)
       erubis (>= 2.6.6)
+      rack (>= 0.9.0)
     browser (0.6.0)
     coderay (1.1.0)
     coffee-script (2.3.0)
@@ -35,10 +36,10 @@ GEM
     mini_portile (0.6.0)
     minitest (5.4.0)
     multi_json (1.10.1)
-    nokogiri (1.6.3)
+    nokogiri (1.6.3.1)
       mini_portile (= 0.6.0)
     options (2.3.2)
-    progress_bar (1.0.2)
+    progress_bar (1.0.3)
       highline (~> 1.6.1)
       options (~> 2.3.0)
     pry (0.9.12.6)
@@ -51,7 +52,7 @@ GEM
     rack-test (0.6.2)
       rack (>= 1.0)
     rr (1.1.2)
-    sass (3.3.10)
+    sass (3.4.1)
     sinatra (1.4.5)
       rack (~> 1.4)
       rack-protection (~> 1.4)
@@ -80,7 +81,7 @@ GEM
     tilt (1.4.1)
     typhoeus (0.6.9)
       ethon (>= 0.7.1)
-    tzinfo (1.2.1)
+    tzinfo (1.2.2)
       thread_safe (~> 0.1)
     uglifier (2.5.3)
       execjs (>= 0.3.0)