Error message to be more appropriate when deleting a DA without deleting the SFC

[mrajora-1]

Description

Error message to be more appropriate when deleting a DA without deleting the SFC

Expected Behavior

Error message should be more suggestive - e.g. DA cannot be deleted unless the SFC is deleted

Actual Behavior

Error message when deleting DA when SFC is not deleted - Distributed Appliance is currently protecting a workload

Steps to Reproduce

• Create a VC (using SDN - Neutron-sfc), MC, DA, DS, SG.
• Create SFC.
• Bind the SG to SFC.
• Now delete the SG.
• Delete DA
• Get an error message - Distributed Appliance is currently protecting a workload
  This suggests that probably there is a SG being protected, whereas, in reality we need to delete the SFC to delete the DA.

Additional Information

WORKAROUND - delete the SFC and then DA delete will be successful

Environment

• OSC Version/Build: Version: 1.0.0-SNAPSHOT (Build:112-g42e1905, 2017-10-11T18:46:02Z)
• Cloud Provider Info:
• Plugin Info:
• Other:

Status

• Reproduced
• In Progress
• Validated => Verified in Version/Build:

Screenshot taken after solving the issue

[arvindn05]

please Handle #544 as part of this change