Migrate core from threads to async awesomeness (#3248)

* Add event loop to the core

* Add block_till_done to HA core object

* Fix some tests

* Linting core

* Fix statemachine tests

* Core test fixes

* fix block_till_done to wait for loop and queue to empty

* fix test_core for passing, and correct start/stop/block_till_done

* Fix remote tests

* Fix tests: block_till_done

* Fix linting

* Fix more tests

* Fix final linting

* Fix remote test

* remove unnecessary import

* reduce sleep to avoid slowing down the tests excessively

* fix remaining tests to wait for non-threadsafe operations

* Add async_ doc strings for event loop / coroutine info

* Fix command line test to block for the right timeout

* Fix py3.4.2 loop var access

* Fix SERVICE_CALL_LIMIT being in effect for other tests

* Fix lint errors

* Fix lint error with proper placement

* Fix slave start to not start a timer

* Add asyncio compatible listeners.

* Increase min Python version to 3.4.2

* Move async backports to util

* Add backported async tests

* Fix linting

* Simplify Python version check

* Fix lint

* Remove unneeded try/except and queue listener appproriately.

* Fix tuple vs. list unorderable error on version compare.

* Fix version tests

tests/test_main.py

@@ -0,0 +1,41 @@
+"""Test methods in __main__."""
+from unittest.mock import patch, PropertyMock
+
+from homeassistant import __main__ as main
+
+
+@patch('sys.exit')
+def test_validate_python(mock_exit):
+    """Test validate Python version method."""
+    with patch('sys.version_info',
+               new_callable=PropertyMock(return_value=(2, 7, 8))):
+        main.validate_python()
+        assert mock_exit.called is True
+
+    mock_exit.reset_mock()
+
+    with patch('sys.version_info',
+               new_callable=PropertyMock(return_value=(3, 2, 0))):
+        main.validate_python()
+        assert mock_exit.called is True
+
+    mock_exit.reset_mock()
+
+    with patch('sys.version_info',
+               new_callable=PropertyMock(return_value=(3, 4, 1))):
+        main.validate_python()
+        assert mock_exit.called is True
+
+    mock_exit.reset_mock()
+
+    with patch('sys.version_info',
+               new_callable=PropertyMock(return_value=(3, 4, 2))):
+        main.validate_python()
+        assert mock_exit.called is False
+
+    mock_exit.reset_mock()
+
+    with patch('sys.version_info',
+               new_callable=PropertyMock(return_value=(3, 5, 1))):
+        main.validate_python()
+        assert mock_exit.called is False