Allow creation of multiline env vars

[pacotole]

Allow creation of env vars with multiple lines using double quotes in .env file

(e.g.)

vault_wordpress_sites:
  examplecom:
    env:
      db_password: ASDFASDFS3534
      ...
      my_private_key: |-
        -----BEGIN RSA PRIVATE KEY-----
        ABCJKgIBAAKCAgEAx7gJFs9GfJ8aaNDyjB9yYmyIcdFgTjRk7K3fYss7AtoAGg7Fh
        ...
        -----END RSA PRIVATE KEY-----