Experimental: hot module reloading for gopherjs and/or vecty.

This requires changes to the gopherjs compiler, so you need to checkout the hmr branch from my fork then run go install.

Run main.go and go to localhost:9090. Try changing the header.go file and see the changes reflected on the page.

Keep in mind, this is an experiment to make something work, no best practices or architecture was put into this yet.