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 Same thing for `response_oai`

```ruby
def response_oai
    @response_oai ||= oai_client.list_records(set: set_handle)
end
```

Also in this case you should use the gash literal ruby syntax as in [ruby style guide](https://github.com/bbatsov/ruby-style-guide#hash-literals)