Description of problem:
All Ceph Overcloud Nodes page fails to show details with error ' Unexpected error encountered' 
production.log
[----] I, [2016-02-27T11:59:39.042089 #12792:563998]  INFO -- : Processing by HostController#show as HTML
[----] I, [2016-02-27T11:59:39.042214 #12792:563998]  INFO -- :   Parameters: {"id"=>"9r6"}
[----] F, [2016-02-27T11:59:39.106835 #12792:563998] FATAL -- : Error caught: [NoMethodError] undefined method `<<' for nil:NilClass
/var/www/miq/vmdb/app/controllers/application_controller.rb:1414:in `block in set_config'
/opt/rh/cfme-gemset/gems/activerecord-4.2.5/lib/active_record/relation/delegation.rb:46:in `each'
/opt/rh/cfme-gemset/gems/activerecord-4.2.5/lib/active_record/relation/delegation.rb:46:in `each'
/var/www/miq/vmdb/app/controllers/application_controller.rb:1387:in `set_config'
/var/www/miq/vmdb/app/controllers/host_controller.rb:30:in `show'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
/opt/rh/cfme-gemset/gems/actionpack-4.2.5/lib/abstract_controller/base.rb:198:in `process_action'


Version-Release number of selected component (if applicable):
cfme-5.5.0.13-2.el7cf.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Add Director environment using ceph nodes, in Infrastructure .
2. Access Ceph Nodes from Infrastructure -> Node Tab.
3.

Actual results:
Error Page seen instead of node page .

Expected results:
All node pages including ceph overcloud nodes are accessible .

Additional info:
PFA production.log , evm.log & screenshot