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
It was not that hard:
https://github.com/rSmart/kuali_rice/commit/7dcfaf68e2eddc0223b197f18b86850292cb0ec2

Now the diff looks much better:
https://gist.github.com/lancespeelmon/3a2d0f80d8b4739e44b2#file-gistfile1-diff-L354

See:
https://github.com/rSmart/kuali_rice/tree/cx-database-attachments