Added secret handler

[bartsmykla]

Signed-off-by: Bart Smykla bsmykla@vmware.com

Description

Added secret handler

Added:

• POST (create secret)
• GET (get all secrets with label informing, that they are   managed by openfaas, because we don't want to return secrets,   which are not related to openfaas)
• PUT (modify the secret - which will be returning only   status 500, because secrets in Docker Swarm are immutable,   so they cannot be changed)
• DELETE (delete the secret)

  Motivation and Context

• [x] I have raised an issue to propose this change (required)

Fixes: #41

How Has This Been Tested?

It was tested by calling the secret endpoints via CURL and looking if intended action was done.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I've read the CONTRIBUTION guide
• [x] I have signed-off my commits with git commit -s
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[ivanayov]

I don't know if there's an agreement not to support secret rm. This would be useful/needed when a secret is wrongly created or needs update.

[bartsmykla]

@alexellis can you review it again? @LucasRoesler maybe you could also have a look?

[alexellis]

Hi @bartsmykla I see it says that you've tested this so I'm going to merge and release.

Let me know if there are any issues with this going to users?

Alex