Better formatting for vapp show
Ignore ruby-version
Guest customization: ensure VM is stopped or stop it
Command network external to add/delete/edit a network

It's a revisited version of lib/chef/knife/vapp/vc_vapp_config_network.rb
Move pretty_symbol to common
vApp network external: don't load parent network for delete

Fix also some options
Add command to add vApp internal networks
Show network details in vapp show
Update README with details about vApp networking
Update CHANGELOG