docs(README.md): update client libraries and projects.
This commit adds information about API version support for all
clients - clearly listing which clients support API v2.

Also, a new nodejs client is added, and a new project as well.
Merge pull request #438 from robszumski/master

feat(docs): add cluster size guide
Merge pull request #439 from lavagetto/master

docs(README.md): update client libraries and projects.
feat(README): splitup the sections into individual files

The README is getting rather large so split it into individual files.

The next step will be rendering these into HTML pages with a TOC so that
they are a bit more navigable.

What do people think of this?
fix(README): link to the configuration file too
fix(Documentation): fixup headers

fixup the headers on the api and tuning sections
Merge pull request #440 from philips/splitup-README

feat(README): splitup the sections into individual files
docs(clients-matrix.md): Introducing the library features matrix.
As support for etcd features is very uneven between different clients,
a feature matrix can help application developers to understand what a
client library can offer them, and also help client libraries
developers to understand what they should work on. I assessed the
features of all client libraries by looking at their master branch on
github, to the best of my knowledge.
Merge pull request #441 from lavagetto/matrix

docs(clients-matrix.md): Introducing the library features matrix.
chore(server): remove web url

web URL is not longer used so remove it from tests and configuration
documents.
Merge pull request #442 from philips/remove-ETCD_WEB_URL

chore(server): remove web url
feat(docs): add front matter to docs that will be synced
chore(docs): modify h2s to h1s, h3s to h2s