Use single quotes

Author: git

spec/gitlab_keys_spec.rb

@@ -49,7 +49,7 @@
     it "adds a key and lists it" do
       create_authorized_keys_fixture
       gitlab_keys.send :add_key
-      auth_line1 = "key-741 AAAAB3NzaDAxx2E"
+      auth_line1 = 'key-741 AAAAB3NzaDAxx2E'
       gitlab_keys.send(:list_keys).should == "#{auth_line1}\n"
     end
   end