Auto apply (global and per-project)

[saitho]

StackHead v1: Since Terraform apply is now done per-project and each project has an own crontab and timer (see #148), the interval should be configurable in project definition. Obviously this can also be used to turn it off for certain projects (i.e. only allowing updates via StackHead deploy command).

Fallback order:

• project definition (if set)
• TBD/Idea: server configuration? (if set)
• CLI configuration (if set)
• StackHead default value

Global and per-project applies should be reimplemented.

[saitho]

As Terraform is dropped, auto-apply is not a built-in thing anymore. If needed, this should be realized by using the Deploy command via CI. There may be a redeploy or update command later.