Improving the use of identifiers for integration tests

DO NOT MERGE

Example for:

https://www.pivotaltracker.com/story/show/79009208
L-rd no. I did that so that the identifiers are useful when we're paging through screens and screens of test logs. That's going to become more important if we go to a multithreaded world where tests are being interleaved. I wanted that, but I didn't want everyone to have to start every test with the following lines:

`public void myTest() {
    final String myTestPid = "myTest-" + randomUUID()`

Admittedly, now they'll do:

`public void myTest() {
    final String myTestPid = getRandomPid()`

but at least there's no hard-coded test name in the code of the test itself.