Switch to metadata.json for Puppet forge releases

Since puppet 3.x, Puppet Labs Forge accept only the metadata.json file
for module description (Modulefile is now deprecated).

This patch :
 - convert the Modulefile to metadata.json.
 - bump major version to 5 (for juno), and deps.
 - switch to stackforge namespace.
 - relax pe version_requirement to 3.x.
 - bump vswitch module deps to 1.0.0 (future semver release)

Change-Id: I2e87acbe5dd6b6fb1681678bbf152bafa15ecac0
Merge "Switch to metadata.json for Puppet forge releases"