mantil deploy should create first project stage

[ksokolic]

While preparing a draft for template texts (currently working on GitHub to Slack) I got to following (simplified) onboarding flow for all new Mantil users: brew install mantil, mantil new --from, mantil aws install, mantil stage new, mantil deploy.
The idea with templates is to serve as landing pages for Mantil where developers will firstly find the template and get to know Mantil through them. That's why it is important to get developers as quickly as possible to that AHA moment Marko is often talking about, to get them developing in the cloud.

With the current flow I need to explain the idea of stages and introduce two commands (stage and deploy). To simply onboarding experience we should expand mantil deploy command to create the first stage for the selected project if stage doesn't already exist.
On mantil deploy:

• if there is more than one node user is first asked to choose on which node he wants to deploy that project, if only one node exist it is taken as default (no need to write anything in second case as it is part of further output)
• user is asked to choose a stage name, but default name development is proposed (it is taken on Enter)

Further output is the same as in stage new command.

Currently if I try to run mantil deploy without existing stage I get:

Note: This doesn't require any change in stage command as it is still needed in current form for all future stage management.