Description of problem:
-----------------------
When the user tries to remove multiple hosts from a cluster at once, the action fails.

For e.g., when the user tries to remove host2, host3, and host4 from a cluster, the following message is seen - 

Error while executing action:

host3:

    Cannot remove Host. Related operation is currently in progress. Please try again later.

host4:

    Cannot remove Host. Related operation is currently in progress. Please try again later.

host2 is removed, but host3 and host4 are not. 

The error message shown should  better convey the reason for failure to remove host3 and host4.

Version-Release number of selected component (if applicable):
Red Hat Storage Console Version: 2.1.2-0.21.beta1.el6_4 

How reproducible:
Always

Steps to Reproduce:
1. Add 4 nodes to a cluster and move 3 of them to Maintenance.
2. Select the 3 nodes moved to Maintenance and click on Remove.

Actual results:
The above described error is seen.

Expected results:
Error message should better convey the reason for failure to remove multiple hosts from the same cluster.

Additional info: