internal documentation for the numerous attributes used in of WSGIHandler; also eliminates pylint warnings about setting undeclared attributes

DummyThread objects are much lighter weight and don't allocate and then immediately delete a Semaphore.

This matters for servers that handle each request in a new greenlet (e.g., gunicorn) because logging caused these objects to be created. Avoiding the Semaphore is especially important on PyPy.

Brought up on IRC.

This involves having read_request raise ValueError subclasses instead of directly logging errors and returning False. This method could already raise ValueError when parsing headers, so callers are prepared for this. It shouldn't be a performance issue because (1) the try block was already being established and (2) these are exceptional situations, not the common case.

Disable test_ssl.test_algorithms test temporarily because the host it uses is not resolvable. Also whitespace cleanup in the list for consistency.

Work around a the worst tuple leak in Cython code under PyPy when releasing semaphores. A complete fix needs a newer cython release.

Mark test__issue6.py flaky everywhere, I'm getting tired of re-running test environemnts on Travis one at a time because of it.

Needs a test case.

Comment-deprecate the undocumented rfile kwarg to WSGIHandler (not using the warnings module because this is a hot code path and also because DeprecationWarning is ignored by default under Py27 anyway) [skip ci]

Working towards improved release support (zest.releaser): compatibility with the pyroma setup linter and fix the issues found. Next up: the manifest.

Fix coverage numbers for top-level statements in __init__.py and friends. Also add some useful platform-specific exclusions.

Add a test for #651 and really fix #651 this time (another manifestation of the same underlying issue as #652)

Support coverage.py in the testrunner and coveralls.io