Fix approve transfer API

refs #6583

MicroServiceChainChoice had been updated to have a foreign key to
MicroServiceChain which can be used directly, instead of fetching the
MicroServiceChain with the correct UUID.  Update approve_transfer for
this change.
Cleanup

Add instruction to API whitelist template, updated code to match.
Whitelisted IPs are now whitespace separated, instead of newline
separated.  Add display functions for MicroServiceChain and
MicroServiceChainChoice.  Cleanup imports.