Merge pull request #51 from rails-girls-summer-of-code/dependabot/bundler/rack-1.6.13

Bump rack from 1.6.4 to 1.6.13

Author: rkh

Gemfile.lock

@@ -108,7 +108,7 @@ GEM
       activemodel (>= 4.0.1, < 5.0)
     quiet_assets (1.1.0)
       railties (>= 3.1, < 5.0)
-    rack (1.6.4)
+    rack (1.6.13)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (4.2.5.1)