Added various tests related to Redmine issue #2525.
Added more tests having to do with trying to get into the wizard without having uploaded a file.
Fixed some existing tests having to do with not having specified a citation.
Added a helper for choosing citation in rspec tests.
Added to the Gemfile a new group "debug" containing the Gems
'selenium-webdriver' and 'pry'; make RSpec use this group and set the Capybara
JavaScript driver to Selenium if the environment variable RAILS_DEBUG is present
and set to "true".

Fixed the BulkUploadHelper module's "choose_citation_from_dropdown" method to
work when run under Selenium.
Bulk Upload RSpec tests: Replaced some inline code with call to method in new
BulkUploadHelper.  Updated two tests to work with new "choose_global_citation"
page. Fixed typo in action name.