Create a demo HTML page for testing solid.js

[dmitrizagidulin]

Create a sample index.html page (that loads rdflib and solid.js) that developers can look at and interact with Solid / LDP dataspaces.

[dmitrizagidulin]

@kidehen Demo page now available at https://solid.github.io/solid.js/demo/
(source code at https://github.com/solid/solid.js/tree/gh-pages/demo ).
Demonstrates login and profile functionality. Will add resource read/write later.
Closing this issue for now.