use openrc credentials to verify swift installation

Don't use the keystone admin token to authenticate, but a real user
instead (using the openrc.sh config file). This simplifies the swift
commands, and makes the verification more consistent with the
verification of other services.

Change-Id: I6a2512cb6cbb2942c9e8673f3f7d960f2f740e8e
backport: none
Improve wording for nova-network vs Neutron

Explain better that the user has two options - and needs to choose one.

Include some minor edits.

Change-Id: I40af701848eddc649cfa33d78ddab6090518d41d
Merge "Improve wording for nova-network vs Neutron"
Merge "use openrc credentials to verify swift installation"