Add clean target to Makefile
Skeleton JS application

- use gulp-angular to bootstrap a basic JS application.
- added basic CORS support to gensend-go so you can develop using
  gulp-server and browser-sync
TODO
 - add CLI switches for alternate port on gensend-go
 - add CLI switch for CORS header support
 - come up with a cleaner place to add the CORS headers, probably
   through the use of middleware