phlsys_makeconduit: refactor to reduce fn size

Refactor a little to reduce the size of the
'get_uri_user_cert_explanation' function.

Test Plan: $ ./precommit.sh
phlsys_makeconduit: fix - always check uri

Fix make_conduit to always check and fix up the supplied uri.

Test Plan:
'arcyon show-config' and supply uri, user, cert but the uri is
incomplete.
Add "system tests" to precommit

Add the existing 'exercise_arcyon.sh' script to the suite of things to
run before committing.

Move 'runtime_tests.sh' -> 'unit_tests.sh'

More 'progress' output from tests.

Test Plan: $ ./precommit.sh
Manually introduce errors to make sure they're reported by
system_tests.sh
add system test for Arcyd

Do some basic smoke testing for Arcyd - create, update and land a
trivial review.

Add a new command to Arcyd 'multi-once' to support the test script.

Add the system test to the 'system_tests.sh' script.

Test Plan: $ ./precommit.sh