See https://github.com/python/asyncio/pull/291 for details.

* Fix ResourceWarning warnings in test_streams
* Return True from StreamReader.eof_received() to fix
  http://bugs.python.org/issue24539 (but still needs a unittest).
  Add StreamReader.__repr__() for easy debugging.
* remove unused imports
* Issue #234: Drop JoinableQueue on Python 3.5+

Move compatibility helpers for the different Python versions to a new
asyncio.compat module.

Move the _loop attribute from the constructor of _SelectorTransport,
_ProactorBasePipeTransport and _UnixWritePipeTransport classes to the
constructor of the _FlowControlMixin class.

Add also an assertion to explicit that the parent class must ensure that the
loop is defined (not None)

Rename Transport.pause/resume to pause_reading/pause_writing. Also relax timeout in test_call_later().