Add Azul Zulu as alternative jre

[Ekaterina001]

Zulu is a tested and certified build of OpenJDK, see zulu.org for more
details.

In order to use Zulu JREs instead of OpenJDK, you must comment out the
OpenJDK line and uncomment the Zulu line in config/components.yml file.

To use Zulu JRE instead of OpenJDK without forking java-buildpack,
set environment variable:

cf set-env <app_name> JBP_CONFIG_COMPONENTS
'{jres: ["JavaBuildpack::Jre::ZuluJRE"]}'

cf restage <app_name>

Issue: #303

[cfdreddbot]

Hey Ekaterina001!

Thanks for submitting this pull request!

All pull request submitters and commit authors must have a Contributor License Agreement (CLA) on-file with us. Please sign the appropriate CLA (individual or corporate).

When sending signed CLA please provide your github username in case of individual CLA or the list of github usernames that can make pull requests on behalf of your organization.

If you are confident that you're covered under a Corporate CLA, please make sure you've publicized your membership in the appropriate Github Org, per these instructions.

Once you've publicized your membership, one of the owners of this repository can close and reopen this pull request, and dreddbot will take another look.

[nebhale]

@Ekaterina001 Is there an https form of this repository? We favor SSL connections wherever possible.

[nebhale]

Note that the contents of the index.yml found at this location, should also use https when possible.

[nebhale]

@Ekaterina001 Good updates. We're going to have a meeting next week to discuss this contribution a bit more, but from a technical perspective we're good to go. Thanks for the quality work and quick updates.