Merge getFileIDs and getChecksums into one operation

After discussion of the propasal on the mailing list: http://ml.sbforge.org/pipermail/bitrepository-devel/2013-June/000324.html it has been accepted by Kåre and Eld that it would be allright to go ahead with such a merge.

The following concerns should be adressed:

• A clear migration strategy needs to be defined, and agreed on across the organizations with production repositories. A scenario could be to create an intermediate protocol version with support for both types of getting file information. This could then be implemented by the pillars. Afterwords the clients and services could be migrated and the getChecksum + getFileIDs operation could be purged from the protocol.
• It should be documented on the individual fileInfo attributes what kind of considerations should be made, like cost, permission, constraints etc.

See: https://sbforge.org/display/BITMAG/GetFileInfos