Also add utility function to allow the node to get the exact details of
the image it is running ('imageinfo').

Some of the taint checks are rather heavy-handed presently.  Pretty much
any vector that could be used by the user to do something as root has
been severed right at the top of the relevant tmcd calls.

Calls affected:

manifest ('blackbox' and 'useronly' taintstates)
rpms ('blackbox' and 'useronly' taintstates)
tarballs ('blackbox' and 'useronly' taintstates)
blobs ('blackbox' and 'useronly' taintstates)
startupcmd ('blackbox' taintstate)
mounts ('blackbox' taintstate)
programs ('blackbox' taintstate)

Taint handling for the 'accounts' call was dealt with in a prior commit.