doc: kick jar_library out of the list of Python-related BUILD file things

back when this was "dependencies", it made sense to list it with Pythonic things. Now, not so much.

Reviewed at https://rbcommons.com/s/twitter/r/598/
dev docs: talk about Travis-CI in one place, not two. Pull requests trigger CI

Mateo was surprised to find out a pull request gets Travis-CI's attention. I'd like to tease him for that, but, uhm, I didn't know it either. So document it. Once it's documented, I can tease the *next* nerd to hit this.

While I was in there, saw an old claim that pants_tests:all ran all the tests. But now our integration tests are separate. So tweaked that wording.

We had two places that talked about running all the tests (ci.sh/Travis). I was too lazy to add this pull-request blurb to both of 'em, so I consolidated. Now one of them is a hyperlink to the other.

Bugs closed: 267

Reviewed at https://rbcommons.com/s/twitter/r/597/
I don't have much idea (hehehe) what I'm doing, but it is working more than it was before.

Idea files are now actually generated and IntelliJ is opened. Codegen also appears to work now, after I moved some code out of ide_gen's __init__ and into its execute(), so that the code actuall gets generated before its called for. External jars work now. I've been testing it out on the jaxb examples and tests.

The code also currently has a mess of print statmements and commented out debugger invocations, as I've been trying to decipher how the old system worked and how the new system is supposed to work.