Make log_to_file accept string level rather than logging package constant

Saves an import, pain in the ass to type all the time.

mitogen/utils.py

@@ -27,7 +27,7 @@ def log_to_tmp():
     log_to_file(path='/tmp/mitogen.%s.log' % (os.getpid(),))
 
 
-def log_to_file(path=None, io=True, level=logging.INFO):
+def log_to_file(path=None, io=True, level='INFO'):
     """Install a new :py:class:`logging.Handler` writing applications logs to
     the filesystem. Useful when debugging slave IO problems."""
     log = logging.getLogger('')
@@ -37,6 +37,7 @@ def log_to_file(path=None, io=True, level=logging.INFO):
     else:
         fp = sys.stderr
 
+    level = getattr(logging, level, logging.INFO)
     log.setLevel(level)
     if io:
         logging.getLogger('mitogen.io').setLevel(level)

tests/data/webproject/serve_django_app.py

@@ -27,7 +27,7 @@ def serve_django_app(settings_name):
 
 def main(broker):
     import logging
-    mitogen.utils.log_to_file(level=logging.INFO, io=False)
+    mitogen.utils.log_to_file(io=False)
     context = mitogen.master.connect(broker)
     context.call(os.chdir, '/')
     #context.call(mitogen.utils.log_to_file, '/tmp/log')

tests/proxy_test.py

@@ -7,7 +7,7 @@ import mitogen.utils
 
 @mitogen.utils.run_with_router
 def main(router):
-    mitogen.utils.log_to_file(io=False, level=logging.INFO)
+    mitogen.utils.log_to_file(io=False)
     child1 = router.ssh(name='u', hostname='u')
     child2 = router.sudo(
         username='sudo_pw_test',