Merge pull request #1814 from MikeMcQuaid/json_runtime_dependencies

formula: return runtime_dependencies in to_hash.

Library/Homebrew/formula.rb

@@ -1618,6 +1618,7 @@ class Formula
         "used_options" => tab.used_options.as_flags,
         "built_as_bottle" => tab.built_as_bottle,
         "poured_from_bottle" => tab.poured_from_bottle,
+        "runtime_dependencies" => tab.runtime_dependencies,
       }
     end