Some improvements (#846)

* #833: do not require sudo on TravisCI

* #N/A: Add Python dev releases to TravisCI pipeline

Inspired by Brett Cannon's advise [1].

    1: https://snarky.ca/how-to-use-your-project-travis-to-help-test-python-itself/

* #837: try and kill proc and its children

* #N/A: show shell information on `thefuck --version`

* #N/A: omit default arguments to get_close_matches

* #842: add settings var to control number of close matches

* #N/A: remove `n` from the list of `get_closest`'s args

tests/shells/test_bash.py

@@ -73,3 +73,8 @@ class TestBash(object):
                                                     config_exists):
         config_exists.return_value = False
         assert not shell.how_to_configure().can_configure_automatically
+
+    def test_info(self, shell, mocker):
+        patch = mocker.patch('thefuck.shells.bash.Popen')
+        patch.return_value.stdout.read.side_effect = [b'3.5.9']
+        assert shell.info() == 'Bash 3.5.9'