fixed --depmap-project-info for scala sources with the same package_prefix

the problem was that we were using same current_target  for all collected source roots. not the proper target this root is part of.

Testing Done:
tests are passing

Reviewed at https://rbcommons.com/s/twitter/r/990/
update release.sh and release.rst to include pantsbuild.pants.testinfra

Moving on, we'll publish two packages at the same time: pantsbuild.pants
and pantsbuild.pants.testinfra to PyPi. While they're sim-released, users
of pants can choose to install pants only if they don't have any
customization to pants thus avoiding the need of writing additional test
cases to which the pantsbuild.pants.testinfra would be helpful.

Testing Done:
I'm not the owner of pantsbuild.pants package on PyPi, so all my testing are local:

build-support/bin/release.sh -t
build-support/bin/release.sh -n

tested both. For the '-n' dry-run, I've also manually injected some failures at pants, pants_testinfra build stages, as well some failures in their testing commands, to have verified the proper command chaining behavior of the bash script.

Bugs closed: 539

Reviewed at https://rbcommons.com/s/twitter/r/1004/
Adds the --<goal>-use-source-root for IDE project generation tasks.

The option will put one entry for each source_root registered that has an active path in the project.
This is useful for Maven style layouts.

Testing Done:
Added unit test and integration test.

Manually tested with:

  pants goal idea testprojects/maven_layout:: --idea-use-source-root

CI is running.

Bugs closed: 558

Reviewed at https://rbcommons.com/s/twitter/r/1006/
Skipping a doc phase should result in transitive deps being skipped as well.

When `--doc-javadoc-skip` or `--doc-scaladoc-skip` are passed to a transitive publish, products generated by those goals will not be available, and should not be depended on in the Ivy javadoc configuration that JarPublish generates. Otherwise, Ivy will fail to resolve the transitive `javadoc` configuration during publishing.

* Expand existing targets to test transitive publishing of java/scala
* Simplify to-string for jar_coordinate of pushdb entries
* Don`t request docs unless they are available for all transitive targets

Testing Done:
new test, and manual publishing with --doc-scaladoc-skip and --doc-javadoc-skip

Reviewed at https://rbcommons.com/s/twitter/r/1011/
depmap KeyError fix

Testing Done:
ci

Reviewed at https://rbcommons.com/s/twitter/r/1015/
comments for mysterious regexen
update and narrow down our "setting up Pants is hard" message

pantsbuild.pants is is a thing. So stop saying it's not installable.

We had commented out stuff about how to install it. Un-comment it.

For a venv-y example, see twitter/commons; not pants' repo, that was only true for a brief time.

BUT, setting up Pants in your code workspace still requires a PhD in Pants-ology. So shift our scary warning over to the setup_repo page.

Reviewed at https://rbcommons.com/s/twitter/r/1007/
Fixup test deps

These were revealed broken by running in non-fast mode.

Testing Done:
$ rm -rf pants.pex dist/ && ./pants build tests/python/pants_test:all

CI is went green here: https://travis-ci.org/pantsbuild/pants/builds/34972075

Bugs closed: 369, 569

Reviewed at https://rbcommons.com/s/twitter/r/1016/
Changes the behavior of goal idea to create a subdirectory named for the project name.

IntelliJ will fail to load the first time if you change the name and try to write the project into
the same directory as an existing project.

Also, enhanced the integration check to examine the contents of the project file when launching "hello"

Testing Done:
Manually confirmed the error "Cannot load module file '/Users/zundel/Development/java/squarepants/idea/foo4568.iml':
File /Users/zundel/Development/java/squarepants/idea/foo4568.iml does not exist
Would you like to remove module 'foo4568' from the project?"

does not occur any more when you change the project name.

Bugs closed: 564, 571

Reviewed at https://rbcommons.com/s/twitter/r/1019/
Merge branch 'master' into lahosken/inherit_docstring
excellent feedback is excellent. commit this before trying wacky improvements