I have installed the curl module as advised by the Flickr module team: https://www.drupal.org/node/2295241#comment-8969037

After installation I receive the following error messages:
Missing argument 2 for variable_get(), called in /home/www/website/modules/chr/chr.module on line 78 and defined - /home/www/website/includes/bootstrap.inc - 587. line.

Missing argument 2 for variable_get(), called in /home/www/website/modules/chr/chr.module on line 79 and defined - /home/www/website/includes/bootstrap.inc - 587. line.