Fixing instance variable behavior

Given that an instance variable may not be set in the controller
This should be gracefully handled in the view by asking .present?
instead of .empty?

nil.empty? raises a NoMethodError
nil.present? == false

[].empty? == true
[].present? == false

Also need to ensure that when we reject the collectible we actually
have an array

[skip ci]
Merge pull request #366 from projecthydra/fixing-instance-variable-errors

Fixing instance variable behavior