Merge branch 'update-libv8' into 'master'

Update libv8

For some reason I could no longer install the previous version of libv8 on my development machine; this version bump fixes that.

I do not know if/how this change affects production environments.

See merge request !1287

Gemfile.lock

@@ -280,7 +280,7 @@ GEM
       addressable (~> 2.3)
     letter_opener (1.1.2)
       launchy (~> 2.2)
-    libv8 (3.16.14.3)
+    libv8 (3.16.14.7)
     listen (2.3.1)
       celluloid (>= 0.15.2)
       rb-fsevent (>= 0.9.3)