Brought createsend gem dependencies up to date.
cane gem without specific version so it doesn't error when doing bundle install for 1.8.7 and ree.
I would rather have the gemspec not contain a dependency (even if only in the development group) which doesn't install on 1.8.7, and continue to run CI on 1.9.7 and ree. So the development dependency on cane has been removed.
Fixed deprecated Mocha require syntax.
Version 2.5.1.
Release history updates for 2.5.1.