Feature/asian ngo dataloader

A data loader for Asian NGO collection(from archive.nyu.edu) with spec and cucs. The data loader uses oai client gem :
https://github.com/code4lib/ruby-oai
I also changed the way method catalog_helper#render_external_links handles exceptions
I added files:
resource_sets/﻿faculty_digital_archive_ngo.rb
﻿specs/resource_sets/faculty_digital_archive_ngo_spec.rb
eatures/cassettes/Search_for_NGO_report.yml
and modified files:
Gemfile
features/search.feature
helpers/catalog_helpers.rb
presenters/url_presenter.rb
deploy.rb

@ekate I don't think we should have conditionals based on Rails environment within these classes. I'd prefer to have another instance variable on `FacultyDigitalArchiveNgo` called something like `load_number_of_records` which we could probably iterate on later if we decide that batch loading is desired. 

Then here you could say 

```ruby
unless load_number_of_records.nil?
   response_oai.first(load_number_of_records).each { ... }
else
   response_oai.eaach { ... }
end