Expect '--include-vcs-ignore'

Seeing if I can get this branch to be able to run
datasette heroku deploy on Travis CI running Ubuntu Trusty

datasette/publish/heroku.py

@@ -96,4 +96,4 @@ def publish_subcommand(publish):
                 create_output = check_output(cmd).decode("utf8")
                 app_name = json.loads(create_output)["name"]
 
-            call(["heroku", "builds:create", "-a", app_name])
+            call(["heroku", "builds:create", "-a", app_name, "--include-vcs-ignore"])

tests/test_publish_heroku.py

@@ -57,7 +57,7 @@ def test_publish_heroku(mock_call, mock_check_output, mock_which):
         open("test.db", "w").write("data")
         result = runner.invoke(cli.cli, ["publish", "heroku", "test.db"])
         assert 0 == result.exit_code, result.output
-        mock_call.assert_called_once_with(["heroku", "builds:create", "-a", "f"])
+        mock_call.assert_called_once_with(["heroku", "builds:create", "-a", "f", "--include-vcs-ignore"])
 
 
 @mock.patch("shutil.which")