Update Rubygems at installation, because stock version is buggy

With the stock version of rubygems supplied i've got a strange errors at deployment like 
```
Gem::RemoteFetcher::FetchError: IOError: Broken pipe (https://rubygems.org/gems/mail-2.5.4.gem)
An error occurred while installing mail (2.5.4), and Bundler cannot continue.
Make sure that `gem install mail -v '2.5.4'` succeeds before bundling.
An error occurred executing 'gear deploy' (exit code: 5)
Error message: Failed to execute: 'control start' for /var/lib/openshift/5236bc26e0b8cd5400000229/jbossas

/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:1146:in `block in do_control_with_directory'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:955:in `process_cartridges'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:1114:in `do_control_with_directory'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:977:in `do_control'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:1319:in `start_cartridge'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:1261:in `block in start_gear'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:78:in `block in each_cartridge'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:961:in `block in process_cartridges'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:959:in `each'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:959:in `process_cartridges'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:76:in `each_cartridge'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/v2_cart_model.rb:1257:in `start_gear'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/application_container.rb:371:in `start_gear'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/application_container_ext/cartridge_actions.rb:379:in `deploy'
/opt/rh/ruby193/root/usr/share/gems/gems/openshift-origin-node-1.13.13/lib/openshift-origin-node/model/application_container_ext/cartridge_actions.rb:241:in `post_receive'
/usr/bin/gear:200:in `block (3 levels) in <main>'
/usr/bin/gear:86:in `do_command'
/usr/bin/gear:198:in `block (2 levels) in <main>'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/command.rb:180:in `call'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/command.rb:180:in `call'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/command.rb:155:in `run'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/runner.rb:385:in `run_active_command'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/runner.rb:74:in `run!'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/delegates.rb:11:in `run!'
/opt/rh/ruby193/root/usr/share/gems/gems/commander-4.0.3/lib/commander/import.rb:10:in `block in <top (required)>'
```
but newer version seems work well.
This commit updates rubygems to the latest version avalable at installation of torquebox