Store CX attachments in the database instead of filesystem

Overriding the original attachmentService with a new DatabaseAttachmentServiceImpl.

Added a new column to KRNS_ATT_T and mapped it to DatabaseAttachment.

fixes rSmart/issues#244
Is this really supposed to reference `org.kuali.rice.kns.bo.Note` instead of `org.kuali.rice.krad.bo.Note`? Or is that just a copy/paste error from an old patch?