Extract deploy script files in each template in order to make standalone platform templates

[Ledoux]

Problem for now is that we have in each template (teleport-flask-webrouter, teleport-flask-websocket, teleport-express-webrouter) redundante script files (deploy, build, push, run) for each platform, ad actually, they should not be necessary required give the platform the user wants to use for its personal project.

Solution would be actually for instance

• add in the teleport-heroku template a file system: backend/servers/deploy-server/scripts/
• to code inside the Teleport application the fact that the deploy-server is an abstract one (like the one we did for frontend-server), and so in that case it has to dump and replace all these files in each server of the user project.