The api-paste.ini accepts not only "=" but also ":" and some services
like Barbican have been using ":" for their default api-paste.ini
files.
[composite:main]
use = egg:Paste#urlmap
/: barbican_version
/v1: barbican-api-keystone
This change allows users to use ":" so that they can update the ini
files with keeping it consistent with the default fules
Depends-on: https://review.opendev.org/813614
Change-Id: I6c79c6d865648cc309a489f6ef371d33673df93a