Merge pull request #118 from elvomka/master

Typo in documentation for add-command.
Fixes #119, bump package.json's engines.node version to be 0.8 or higher.
Merge pull request #120 from ncalexan/use-node-version-0.8

Fixes #119, bump package.json's engines.node version to be 0.8 or higher...
Fixes #122, version compare logic flaw.