Fixed and expanded tests for Donate link

Was failing if eol-private was not checked out.  Required overiding
three values from Rails.configuration, use_secure_acceptance,
donate_header_url, and donate_footer_url.
Fixed iNat and Flickr tests

The URL constant for iNat is now in the config/environment.rb.  The
Flickr variables are now global variables in config/environment.rb.