0.13.0

• node_modules are now ignored.
  Some tile authors have started experimenting with testing JS migrations and were seeing tons of files show up in their tile builds, which caused Ops Manager to complain loudly
• Using a helper without specifying the flag now returns an error
  For example, using $( property "foo" ) will return an error containing --properties-directory if that flag was not provided
• Internal APIs to enable experimental om config-template feature.