Fix Gem::Dependency, use >= in version checks

Gem::Dependency no longers supports an un-name dependency (at least as
of Ruby 2.1). We now give a name to our dependency ('scalr') when we do
version checks.
Repository URL prompt: add an example
Release: 7.4.16
Merge pull request #80 from Scalr/release-7.4.16

Release 7.4.16