Refactor pattern to use == rather than 'in'.
Improve timeline logging and timestamp everything that's logged.
Do not run checks in fixture finalization if test failed.
* Fix#811: new socket server to receive pid and port for subprocesses
* Install test dependencies from test_requirements.txt on Travis
* Multiproc support can't handle os.fork() as implemented.
On Python 3.4+, use set_start_method('spawn') to ensure that multiprocessing module doesn't use fork.
On lower versions, skip the test.
* Restrict the multiprocessing test to Windows for now.
* Testing framework for timeline-based tests.
See pytests/helpers/timeline.md for a detailed description.
Fixes#832, and lays the groundwork for #833.
* Upgrade pip to most recent version before installing prerequisites on Travis.
