Add ability to create secrets via barbican.client state

This patch adds ability to create secrets in barbican using client state
Secret can be created with or without payload, and payload can be added
later. Also there is possibility to pass path to file which should be
added as payload. Also payload can be encoded to base64 via client state

Depends-On: Idad75a8445a874e62c2e2d729cb8e98d7a37d6bd

Change-Id: Ia455622550d4456c594e6aa98c77aa3a1b3ab628
Related-Prod: https://mirantis.jira.com/browse/PROD-18731
5 files changed