Issue #491 - Move logger globals for Python bug

Shift the `log.py` logger globals to the beginning of the file to avoid
a Python bug that causes spurious "annotated name can't be global"
errors when mypy lints the files.

See here for the issue report:
https://bugs.python.org/issue34939

Clarification on the ticket marks this as a bug and a fix was added.
This avoids the error in Python 3.7.

ait/core/log.py

@@ -39,6 +39,13 @@
 logging.addLevelName(COMMAND, "COMMAND")
 logging.addLevelName(PROGRAM, "PROGRAM")
 
+logger = None
+crit: Optional[Callable[[str], str]] = None
+debug: Optional[Callable[[str], str]] = None
+error: Optional[Callable[[str], str]] = None
+info: Optional[Callable[[str], str]] = None
+warn: Optional[Callable[[str], str]] = None
+
 
 class LogFormatter(logging.Formatter):
     """LogFormatter
@@ -313,14 +320,4 @@ def notice(*args, **kwargs):
     logger.log(NOTICE, *args, **kwargs)
 
 
-# These are "guaranteed" at runtime to be not-None. Marking this as
-# type `Any` addresses mypy issues where log calls are marked as
-# "None" being not callable.
-logger = None
-crit: Optional[Callable[[str], str]] = None
-debug: Optional[Callable[[str], str]] = None
-error: Optional[Callable[[str], str]] = None
-info: Optional[Callable[[str], str]] = None
-warn: Optional[Callable[[str], str]] = None
-
 init()