zerocloud: minor tweaks/revisions to dev env docs
Merge pull request #43 from larsbutler/dev-env-tweaks

zerocloud: minor tweaks/revisions to dev env docs
Complete rewrite of ZeroCloud overview
index: change "getting start" to "contributing"
index: move "contributing" section to the bottom

This leaves topics which are more relevant to most developers at the top
of the page.
index: update "welcome" heading
clitools: update page title

Replaced "CLI" with "Command Line".
clitools: replace Zwift with ZeroCloud

Zwift has long been deprecated.
clitools: reorganize/rewrite

- zpm is at the top, instead zvsh/zvapp (zerovm-cli)
- Reworded the subproject links to zpm and zerovm-cli
zerocloud/overview: update overview heading
Add ZeroVM core docs
index: Reorganize index completely, plus new intro
zerocloud/overview: minor revision/rephrasing
Merge pull request #44 from larsbutler/overhaul

Docs overhaul
minor sudo fixes
Merge pull request #46 from bunchc/ZeroCloud

Minor fixes for execution within the Vagrant VM
index: fix a typo (missing word)
zerocloud/devenv: add var exports to client config
Typo in rejoin-stack

changed rejoin_stack with rejoin-stack, since that was what devstack
had after building it with vagrant.
zerocloud: "Snakebin" application tutorial, part 1