Original function name in callback meta-data

[ewilde]

Description

Adds original function name in callback meta-data X-Function-Name

Motivation and Context

• [x] I have raised an issue #82 to propose this change (required)

How Has This Been Tested?

Tested on docker swarm:

• Invoke function a (in this example called echo) asynchronously provide callback to function b
• verify header is set

Logs for function b

2019-12-10T21:17:05Z 2019/12/10 21:17:05 stderr: 2019/12/10 21:17:05 Function: [echo], status:[200], time:[0.001863], body:OK

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] 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.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly see: https://github.com/openfaas/docs/pull/195.
• [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.
• [ ] All new and existing tests passed.

[alexellis]

This branch has conflicts that must be resolved. Use the command line to resolve conflicts before continuing

👨‍💻

[alexellis]

@ewilde please see my comment.

[ewilde]

@alexellis PTAL, rebased