Re-vendor queue-worker publisher for reconnect

[alexellis]

Description

• re-vendor queue-worker for publisher via 0.6.0
• bump queue-worker version to 0.6.0 in docker-compose.yml for
  AMD64
• use new naming for NATS of nats -> NATS in variables where
  required
• add default reconnect of 60 times, 2 seconds apart.

Motivation and Context

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

Partial fix of: #1031

How Has This Been Tested?

Tested via PR in nats-queue-worker repo: openfaas/nats-queue-worker#49

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)

Breaking change in type names nats -> NATS when used as prefix or in medial position for types.

Checklist:

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