fix M2Crypto 0.27.0 test compatibility

the different behaviour was introduced in 0.28.0, not
in 0.27.0, so the test needs to check against 0.28.0

also (0, 27, 0) > (0, 27) evaluates to True
(this is where the original confuson came from)

unit_tests/test_tlslite_utils_keyfactory.py

@@ -173,7 +173,7 @@ def test_key_parse_using_openssl(self):
 
         # XXX doesn't handle files without newlines
         # old version of M2Crypto return a Null, in Python3 it raises exception
-        if M2Crypto.version_info >= (0, 27, 0):
+        if M2Crypto.version_info >= (0, 28, 0):
             exp = M2Crypto.EVP.EVPError
         else:
             exp = SyntaxError