test-ui: use new flickr plugin

flickr-auth.[ch] was replaced by their oauth alternatives and main.c was
rewritten to use them.

Into authenticate flickr popup window was added text entry to enter the
verifier given by flickr.

https://bugzilla.gnome.org/show_bug.cgi?id=697175



Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>