Major Description
When Slider view parameters are provided at random, failures happen. The exception messages should be more descriptive of what has happened.
1) Create slider instance with random settings (like "123")
2) Fill properties in such way:
url : "http://ambari.server:8080/api/v1/clusters/c1"
username: "http://ambari.server:8080/api/v1/clusters/c1test"
slider user - random, like "admin"
3) Go on this slider. Warning "ambari.server" appeared
