Server: List, load, and save graphs to local FS

- Graphs list, load, save to FS
- Texture images listing
- moved browser code to browser/ for serving
- added handlebars.js for templating
- moved 3rd party scripts to vendor/
- add running instructions to README.md
Merge pull request #1 from engijs/fs_server

Simple server to list, load, and save graphs to local FS