Releasing the support for PURLs from Ruby Gem repository

Full Changelog: v0.5.0...v0.6.0

Add support for npm-registry related purls

Full Changelog: v0.4.0...v0.5.0

Releasing the support for PURLs from PyPi

Full Changelog: v0.3.0...v0.4.0

Enhanced the unittest suit with gitlab cases

Confirms support for Gitlab download urls

Releasing the support for GitHub and BitBucket PURLs

v0.2.0

Fix typo in README file