Disable Javadoc linter with Java 8
Fix SelectorTest for Java 8 by using a Map with predictable iteration order
Revert "remove jdk8 until we fix all the tests for it"

This reverts commit 9d423a3b3f536b2d75ab7782fbd1711f2d053b2b.
Merge pull request #615 from joschi/java8

Make tests pass with Java 8