Be safe, don't let friends use RawConfigParser

Replace uses of ConfigParser() and RawConfigParser() with
SafeConfigParser().

Change-Id: I78395eae381e1b911ab6b48c572665f4601ec315

pbr/tests/util.py

@@ -51,7 +51,7 @@ except ImportError:
 
 @contextlib.contextmanager
 def open_config(filename):
-    cfg = configparser.ConfigParser()
+    cfg = configparser.SafeConfigParser()
     cfg.read(filename)
     yield cfg
     with open(filename, 'w') as fp:

pbr/util.py

@@ -201,7 +201,7 @@ def cfg_to_args(path='setup.cfg'):
     """
 
     # The method source code really starts here.
-    parser = configparser.RawConfigParser()
+    parser = configparser.SafeConfigParser()
     if not os.path.exists(path):
         raise DistutilsFileError("file '%s' does not exist" %
                                  os.path.abspath(path))