Update phpunit to 4.0.0 in CONTRIBUTING.md, tests/Bootstrap.php, and Zend\Test\composer.json
based on #6909
#6942 - direct links to contributors resources
#6942 - RFCs as github issues are good enough
#6942 - simplifying testing setup/installation/run explanation
#6942 - s/http/https
#6942 - clarifying: security issues should not land in the public issue tracker
Merge branch 'docs/#6942-#6909-phpunit-4.0-in-docs' into develop

Close #6942