py3: Add Python 2/3 compat module

Keep all the hacks in a single place. This looks like all we need, so no need
to depend on six.

mopidy/utils/compat.py

@@ -0,0 +1,24 @@
+import sys
+
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+
+if PY2:
+    import ConfigParser as configparser  # noqa
+    import Queue as queue  # noqa
+    import thread  # noqa
+
+    string_types = basestring
+    text_type = unicode
+
+    input = raw_input
+
+else:
+    import configparser  # noqa
+    import queue  # noqa
+    import _thread as thread  # noqa
+
+    string_types = (str,)
+    text_type = str
+
+    input = input