Add dummy readme in examples/src/../scala/hello for Intellij plugin integration tests.

We added capability to the pants plugin to index non target owning files e.g. deploy scripts or READMEs
here https://rbcommons.com/s/twitter/r/1338/

We added the for the plugins.
Integration tests for Intllij plugin

Testing Done:
yes.
https://github.com/pantsbuild/pants/commit/d0fc5d05e8fae14311bab4cb7e664fa23fb02a8c

Reviewed at https://rbcommons.com/s/twitter/r/1356/
Support for the --kill-nailguns option was inadvertently removed, this puts it back.

The kill-nailguns flag was being read through old_options.cleanup_nailguns

Also updated the nailgun timeout logic to try and pinpoint transient errors in CI if it
happens again.

This reverts the change at https://rbcommons.com/s/twitter/r/1345/ which is redundant with this one (and not as effective.)

Testing Done:
CI Passed.

Bugs closed: 803

Reviewed at https://rbcommons.com/s/twitter/r/1352/
scala_specs: mention specs lib in the docstring; mention junit works, too

because not all Scala tests are scala_tests

Bugs closed: 622

Reviewed at https://rbcommons.com/s/twitter/r/1326/
Cache files created by (specially designed) annotation processors.

These annotation processors (so far, only twitter.common.args) write a file into META-INF which lists all of the files they created. Make pants process that file to decide which files should go in the artifact cache.

Testing Done:
Ran integration tests.

Bugs closed: 132

Reviewed at https://rbcommons.com/s/twitter/r/1250/
Revert "Cache files created by (specially designed) annotation processors."

This reverts commit e556eaa08f9c8e1be64a694d739283235d6989b0.

Apparently, this fails in CI for reasons I don't understand, so I'm
reverting it until I can figure it out.
doc: fix JVMProjects problems I didn't want to think about in rb/1176

Don't claim 'goal jar' is one of "The Usual Commands". It's kind of obscure and scary.

An extra "is" was in code font. Yeah, "is" is valid Python. But this wasn't Python, this was English.

Updated ivy mention: use new flags/config.

Tweaked nailgun description.

While I was in there: removed a section on getting help. It was redundant with
first_tutorial, except that it hadn't kept up to date :-(

Reviewed at https://rbcommons.com/s/twitter/r/1358/
doc: nailgun 5 seconds -> 10 seconds

Bugs closed: 804

Reviewed at https://rbcommons.com/s/twitter/r/1363/