Updates for new kazuki, javadoc
WIP chopping out nexus-scheduler

This will still not compile, as YUM needs to
depend on quartz plugin as it has some very
involved task handling logic, the single case
of it in OSS.

Everything else should be okay, as it's about
firing and forgetting background tasks.

nexus-it-helper-plugin needs to be revisited too
as it also must to depend on quartz to
test for given task by ID