cms: Use universal_newlines=True in subprocess.Popen()

The Python documentation states that "the type of [the first argument of
subprocess.communicate()] must be bytes or, if universal_newlines was True, a
string"[1]. Currently, in Python 3, a text string is given to
subprocess.communicate(), even though the process was created with
universal_newlines=False (the default value).

Rather than converting strings to bytes (and the other way around) everywhere
in the code, just create the process with universal_newlines=True. The side
effect is that '\n', '\r\n' and '\r' will be recognized as ending lines[2],
which should not be an issue.

[1] http://docs.python.org/3/library/subprocess.html?highlight=popen#subprocess.Popen.communicate
[2] http://docs.python.org/3/glossary.html#term-universal-newlines

Change-Id: I668b187ba8ed00ad6d55ec487af623b79b21589d

keystoneclient/common/cms.py

@@ -114,7 +114,8 @@ def cms_verify(formatted, signing_cert_file_name, ca_file_name):
                                 "-nocerts", "-noattr"],
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE,
-                               stderr=subprocess.PIPE)
+                               stderr=subprocess.PIPE,
+                               universal_newlines=True)
     output, err, retcode = _process_communicate_handle_oserror(
         process, formatted, (signing_cert_file_name, ca_file_name))
 
@@ -225,7 +226,8 @@ def cms_sign_text(text, signing_cert_file_name, signing_key_file_name):
                                 "-nocerts", "-noattr"],
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE,
-                               stderr=subprocess.PIPE)
+                               stderr=subprocess.PIPE,
+                               universal_newlines=True)
 
     output, err, retcode = _process_communicate_handle_oserror(
         process, text, (signing_cert_file_name, signing_key_file_name))