Support coverage.py in the testrunner and coveralls.io

Add python 3.5 selectors test, and remove the devpoll selector under 3.5. also update the monkey documentation.

Honor the timeout argument to Popen.communicate if there is no way to communicate with the child. Fixes a Python 3.5 test failure; add the Python 3.5 subprocess test suite.

See the detailed changelog entry. This brings correctness, debugging,
and performance benefits. It further matches the already documented
and specified restrictions on application-provided header and status
line values.

Python 3.5 regression

Unify and simplify the implementation of Queue.get and Queue.put. Fixes #647 (add a test case for that scenario).

Fix a regression introduced with PyPy support in 715a7071 that caused the timeout to be ignored for socket.makefile objects under Python 3. Fixes #644

Patch signal.signal(SIGCHLD) to cooperate with child watchers