[mms_codec] Ignore non-multipart attachments
[mms-dump] Handle non-multipart attachments
[test_mms_codec] Added test for non-multipart attachment
[mms-engine] libwspcodec >= 2.2 is required
[test_mms_codec] Added couple more m-retrieve.conf tests

Those are interesting PDUs from the actual field tests.
All the confidential information has been wiped out.
[mms-dump] Fixed decoding of PDUs containing no attachments
Merge pull request #28 from monich/non-multipart

Handle non-multipart attachments