add dep

Author: dlesbre

Gemfile.lock

@@ -248,6 +248,7 @@ GEM
     libv8 (3.16.14.19.1-x86_64-linux)
     liquid (4.0.4)
     listen (3.9.0)
+      rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     logger (1.6.1)
     mercenary (0.3.6)