Use WeBLAS for GPU acceleration

[waylonflinn]

You mentioned in the Machine Learning subreddit that you'd like to see if weblas could boost performance of this library. I'm interested in that as well.

Weblas is almost ready for this sort of thing (pipelining of existing operations should be done by this weeked). This issue is here to remind us both to create a branch and a PR, and see what happens. 🚀

[danrubins]

+1 really excited to see if this works

[waylonflinn]

Here's a demo I worked up that shows how to use the new pipeline features in weblas to get very good performance on neural net forward pass:
http://waylonflinn.github.io/DeepBeliefSDK/

[transcranial]

@waylonflinn very, very cool, thanks! Will let you know when I make some progress.

[waylonflinn]

Happy to help in any way I can! At mention me in your PR with questions or email me at gmail with my github username. 👍🏻🎯
Excited to see where this goes!