refactoring parameter_sets_controller_spec
introduce _host_parameter_fields action

- this is an ajax action
- returns fields for host parameters in html
- JS inserts the html into the form
- initialize run with an appropriate submitted_to value
add test case
trigger change event after host_parameter fields are updated
add rendered file
Merge pull request #252 from crest-cassia/bugfix_host_parameter_is_not_correct

Bugfix host parameter is not correct