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
features/cassettes/
@ekate it doesn't look like anything actually changed in this file. Can you revert the whitespace changes?

@NYULibraries/hydra, for reference, I generally try to follow the [Ruby style guide](https://github.com/bbatsov/ruby-style-guide) which [GitHub uses](https://github.com/styleguide/ruby) as well. I think we should adopt this style guide as much as is practical, so it's easy for team members to work on each other's code.