Added Blue/Green-Deployment

[samedguener]

• Please refer to https://docs.cloudfoundry.org/devguide/deploy-apps/blue-green.html and https://github.com/orange-cloudfoundry/terraform-provider-cloudfoundry for reference
• fixed issue, where app won't start after new upload

[ArthurHlt]

Thank you for your contribution.
We actually plan to add blue green deployment but we need to discuss with @mevansam about what strategy to adopt.

You can join us on the opened discussion #25

[gberche-orange]

@samedguener besides blue green support #25, this pr mentions "fixed issue, where app won't start after new upload".

Would you mind submitting a distinct PR for this issue with a description of the symptoms when the issue reproduces ?

I close this pr for now until we resume #25

thanks again!

[samedguener]

Opened an issue for this, describing the problem #32.

Best,
Samed

[gberche-orange]

thanks @samedguener !