Atlantis.yaml improvement - Allow project name to have slashes

[mechastorm]

Issue

In this example of a partial atlantis.yaml

version: 2
projects:
  - name: terraform/iam/preprod
    dir: terraform/iam/preprod
    workspace: default
    workflow: preprod

If someone to name their project name as terraform/iam/preprod this would result in an error in Atlantis when writing the plan file

Example:

Error: Error writing plan file: open /var/atlantis/repos/myuser/myrepo/2/default/terraform/iam/preprod/terraform/iam/preprod-default.tfplan: no such file or directory

The workaround is to not put / in project name

Atlantis Version

0.4.7

Desired Behaviour

The project name should be able to support slash. Either Atlantis escapes them/replaces the character internally or validate and not accept the config if it has a slash in the name.

We prefer to have slashes in our project name so that it matches the path of our terraform code directory in our monolith terraform repo.