ncp dependency, path join, manifest v2

Add ncp dependency and implement recursive copy with ncp
Use path join for portability
Use path join in test.
Complete adding windows compatibility

New dependencies:
* wrench - for easy recursive file operations
* archiver - tool to zip files
* buggerstream - in memory data stream to write archiver data

Removed dependencies:
* (*nix) operating system
* zip command

The rest of the path joins using + were found and fixed.
Update README

Remove zip dependency
Update example javascript to use cross-platform join rather than plus to
concat directories
Fix command line version of keygen

Calling keygen from the command line was broken, because cb() is filled
in by commander but it is not a function
Rename path.exists to fs.exists to remove deprecated warning
Bump version
Update minimum node version after ubuntu testing
Fix line endings
Update node version in .travis.yml
Merge pull request #10 from adotout/master

Windows Compatibility