Upgrades, add credentials to astute.yaml

Feature `access control on master node`
was introduced in 5.1 release.
In this feature fuelmenu generates credenitals
and saves them in /etc/astute.yaml file.
Before upgrade for this featuer we need to
add default credentials to the file for 5.0.X
versions.

Closes-bug: #1333204
Change-Id: I415439bc9211c2fc43cce226d9127ca7767eb7b8
Merge "Upgrades, add credentials to astute.yaml"