The keystone configuration used the 'connection' option in the
'sql' section of the keystone.conf file. This option is deprecated
in favor of 'connection' in the 'database' section.
The keystone setup code is changed to use the option in the new
section rather than the deprecated one.
Change-Id: I62fd2f50ded3b8848e9e5225e88c80ed8fed3bff