Parse Options: parse options in query params

Now you can use any less parse options in query params.

Include them like this:

POST /?options=x

Where x is a JSON-encoded string of parser options accepted by less.
README: describe new features

Including sessions which was added previously.
Merge less-options (#3) into master

Parse Options: parse options in query params

Now you can use any less parse options in query params.

Include them like this:

POST /?options=x

Where x is a JSON-encoded string of parser options accepted by less.

Conflicts:
   README.md
   * Both added to the end of the file.