Add Version manager

[azukaar]

Add a CLI tool to manage version of the package

# bump the version

g version minor
g version major
g version patch

Use (already included) : https://godoc.org/github.com/Masterminds/semver

• Add a --commit option to commit the version change directly (Need to use something like https://github.com/src-d/go-git)

• The publish command would have the same flags (minor major patch) that would bump the version before publishing if used

• The version cli command can be hooked

• Add versionChange() script function (see getDependency function on how to call a provider the JsVM) (with minor/major/patch argument)

• Add semverBump() that take a string and return the bumped string (with minor/major/patch argument)