use watchify to reduce re-build times
Created by: MartinHN
Hi again, I was tired to wait 12s build + page refresh at every changes made on my almost out of date osx-machine , this pr takes re-builds down to 2s for me using watchify, so compiling only the needed part
this PR adds the new npm command : watch-browser
- feel free to change scripts name / implementation, thats just a proposal,
- i can add this to launcher too if needed