[SyncEvolution] Move "getMimeType" from SyncSourceSerialize to SyncSource

Hi Why is getMimeType specific to SyncSourceSerialize? Any SyncSource should provide his preferred mime type, thus it looks more resonable to move it to SyncSource base class. While I am adding the contentType filed in the SAN message, I found there is not a general way to get the format the backend is using, basically we need to: getSyncSourceType check syncSourceType.m_format check syncSourceType.m_backend if m_format is empty, this needs to match to a bunch of backend predefined strings like "Evolution Addressbook", etc. I am thinking using getMimeType for one stop solution but it is not a method in SyncSource class at the moment. What's your ideas on this? I would like to move it to the base class if no objection. -- Regards, Chen Congwu Moblin China Development