v30 changelog highlights

- Enhanced models and migrated Nginx, Github, Alpine, NVD, OpenSSL and Redhat Importer.
- Enhanced the web UI with a brand new UI based on the same overall look and feel as [ScanCode.io](http://scancode.io/).
- Added new importers like PYSEC, Pypi and GitLab
- Added aliases of a vulnerability in the API vulnerabilities/ endpoint.
- Added a new `cpe/` API endpoint to lookup for vulnerabilities by CPE and another aliases/ endpoint to lookup for vulnerabilities by aliases
- Added bulk search support for CPEs.
- Added fixed packages in vulnerability details in packages endpoint
- Enhanced Package endpoint will give fixed packages of only those that matches type, name, namespace, subpath and qualifiers of the package queried.
- Added filters for vulnerabilities endpoint to get fixed packages in accordance to the details given in filters: For example, when you call the endpoint this way ``/api/vulnerabilities?type=pypi&namespace=foo&name=bar``, you will receive only fixed versioned purls of the type ``pypi``, namespace ``foo`` and name ``bar``.
- Added is_vulnerable property to fixed and affected package in packages endpoint
- Added authentication for REST API endpoint.
- Added data license CC-BY-SA-4.0 as this is the highest common denominator license among all the data sources we collect and aggregate.