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, we can probably use Ruby's [implicit begin block](https://github.com/bbatsov/ruby-style-guide#begin-implicit) here. Also, if possible, please outdent the rescue block 1 soft-tab (2 spaces) and add a newline at the end of the file.