Feature request: enhance the error message the user sees if communication with Github fails during the bootstrap

[marcpaterno]

The current bootstrap script does an excellent job of logging detailed information to help an expert discover the cause of a failure.
But the log file used for this is highly non-trivial, and not friendly for the non-expert.

In addition to the detailed logging, it would be good to produce a simple-to-understand user-facing error message if the bootstrap fails because of a problem communicating with Github. While such outages are not common, they do happen and users will encounter them. An error message the user can understand when this happens will probably avoid some failure reports being sent to the Service Desk, because the user would know to just try again later.

[marcmengel]

We should also check for:

• disk full in $TMPDIR
• disk full in destination directory