bin/deploy should fail when curl fails to find appropriate certificate

[heather999]

When using lsstsw/bin/deploy at NERSC and at Harvard, I typically lack administrative access and have trouble with the curl commands for git and eups due to the missing certificate, as mentioned here:
https://confluence.lsstcorp.org/display/LSWUG/Building+the+LSST+Stack+from+Source
It's easy enough to fix by adding a --cacert parameter to the curl command. However, it is very difficult to spot the problem given the extensive output from ./bin/deploy. It would be much better if the script could report a hard failure due to the unsuccessful curl command(s). Otherwise, it may appear to a user that everything was set up, but then problems ensue when trying to use eups or git-lfs, for example.

[jdswinbank]

Added to JIRA as DM-6109.