Ability to upload and attach files to client/loan records

Similar to the ability to upload and attach a client photo, we'd like to add support for uploading and attaching files (pdfs, word docs, etc.) to a client record.

This is useful in providing one centralized interface for the MFI in which they can access their client records from any location.

Initial implementation would be simple - just the ability to attach a file and metadata corresponding to that file so it could be queried in reports, etc.

Over time and in Mifos X we could integrate with a more sophisticated document management module.