Collapse output of –search and –list (and gem_server) operations so that each gem is listed only once, with each of its versions listed on the same line.
bin/gem: new –upgrade-all option allows one to upgrade every installed gem
new #required_ruby_version attribute added to gem specification for specifying a dependency on which version of ruby the gem needs. Format it accepts is the same as the Gem::Version::Requirement format:
spec.required_ruby_version = “> 1.8.0”
–install-stub defaults to true, so library stubs are created