Adapt for elliptics binding > 2.24.19
Fix compatability with elliptics api
Add some options to elliptics backend configuration.

Describe options. Also add links to documentation.
Add Elliptics backend description in README.md
Move example to README.md
Merge pull request #169 from noxiouz/add_elliptics_usability

Fix compatability with LTS Elliptics API and add some docs.