Implement a cmdline tool

[jeromeetienne]

Hi, i love guri vr and its concept of using natural language to generate AR/VR content. I would like to contribute to make it even better. This command line tool is step toward that.

Here is a command line tool. it will allow to generate content directly from the command line. So it get generated without servers. It works offline. It works fast too.

it would look something like that

Guri-vr -o output.html 'display an image located at https://s3.amazonaws.com/gurivr/logo.png'

Maybe to install it with a usual npm

npm install guri-vr

This pull request is a first draft, to get the conversation started