Acceptance tests should use "subscription-manager status"

[LalatenduMohanty]

Currently we use [1] subscription-manager version to check if the registration happened successfully or not.
I tested it found that it returns exist code 0 in case of unregistered machines too though the status output changes to server type: This system is currently not registered.

So I think we should use subscription-manager status as per --help
status Show status information for this system's subscriptions and products
Also I tested it for registered system and unregistered system and the exit code and output both changes correctly.

For unregistered systems

[vagrant@rhel-cdk ~]$ sudo subscription-manager status
+-------------------------------------------+
   System Status Details
+-------------------------------------------+
Overall Status: Unknown

[vagrant@rhel-cdk ~]$ echo $?
1

For registered systems

[vagrant@rhel-cdk ~]$ sudo subscription-manager status
+-------------------------------------------+
   System Status Details
+-------------------------------------------+
Overall Status: Current

[1] https://github.com/projectatomic/adb-vagrant-registration/blob/master/features/support/env.rb#L56