Improve cli documentation

- Copy changes to make it more concise
- Improve installation steps documentation
- Surface available commands and options:

    $ origami-build-tools

Now outputs:

```
Usage: origami-build-tools <command> [<options>]

Commands
   install  Install system and local dependencies
   build    Build module in current directory
   demo     Build demos into the demos/ directory
   verify   Lint code and verify if module structure follows the Origami specification
   test     Test if Sass silent compilation follows the Origami specification
   docs     Build module documentation into the docs/ directory

Options
   [--watch]               Re-run every time a file changes
   [--local]               Build demos locally, and run them in a browser
   [--updateorigami]       Update origami.json with the latest demo files created
   [--demoConfig=<path>]   Path to the demos config file. (default: demos/src/config.json)
   [--js=<path>]           Main JavaScript file (default: ./src/main.js)
   [--sass=<path>]         Main Sass file (default: ./src/main.scss)
   [--buildJs=<file>]      Compiled JavaScript file (default: main.js)
   [--buildCss=<file>]     Compiled CSS file (default: main.css)
   [--buildFolder=<file>]  Compiled assets directory (default: ./build/)

Full documentation: http://git.io/bBjMNw
```