Array#wrap of multi-value input collection

Resolves the following:
    NoMethodError: undefined method `each_with_index' for nil:NilClass
      multi_value_input.rb:14:

Removing MultiValueWithElements input
  * This is something that may need to be tackled later, but for now
    it needs to go as it is interfering with specs
Merge branch 'fixing-multi-value-collection-input' into update-article-metadata

* fixing-multi-value-collection-input:
  Array#wrap of multi-value input collection

Conflicts:
	spec/inputs/multi_value_input_spec.rb
Tweaking how future date validation works

The attribute for validation was hard-coded. I believe this was an
artifact of copying the validator from another repository.

While doing this, I removed the custom class, instead creating a
dynamic class that can be disposed of at the cleanup's leasure.
Adding multi-value presence validation

Given that we are allowing multi-value for a given attribute, we
need to better handle the presence of that attribute.

Consider:

    class MyModel
      validate :contributor, presence: true
    end

    object.contributor = ['']
    object.valid? == true

When in fact we likely mean for it not to be true.

Conflicts:
	app/repository_models/article.rb