JOHNSON-20 Support Platform 5 & Java 11

• Bumps major version to 4.0.0

• Updates dependencies to match Platform 5

• Updates Mockito to 2.20 for Java 11 support

• Ignore/disable JohnsonDispatcherServletTest since Powermock does not support anything past Mockito 2.8.9, and 2.8.9 does not support Java 11

• Remove documentation site deploy as the host no longer exists and releasing fails as a result

Note: This targets the java11-compatibility branch for now, will merge that to master once more of the Platform 5 work is done. I've also release a snapshot version 4.0.0-106b6d5 for products to begin testing with.