Add UI and backend support for creating EGI machine

[emanueldima]

• User logs in, clicks on some "Create EGI machine" and uploads EGI certificate
• GEF starts a special Docker container that creates the EGI VM, getting back an IP and user account (selected by GEF)
• GEF runs a procedure to configure the Docker connection with EGI
• When starting a service, the user must be able to select the location of the execution: either on the default, common, Docker service; or on the EGI machine