"gulp vulcanize" task doesn't work

[hawkw]

See e991ba4.

I've been trying to set up a gulp vulcanize task for concatenating Polymer web components prior to deployment (as discussed in #6), but it doesn't seem to be working correctly.

The task currently doesn't output anything to the destination directory. I checked the command-line vulcanize tool, and it works fine, so I am not really sure what's up. I've done a bit of research and cannot seem to figure out what I'm doing wrong.

If anybody else wants to check out my code in e991ba4 and try and get this working, that would be awesome. I'll keep hacking on it, but I am by no means a Gulp expert, so if someone with more experience (@ArcticLight?) could take a look at this, that might help.