Turn on validate customers and hmac by default

[martindekov]

Setting the customer validation and hmac validation on by default also moving customer validation into its own function so it can be tested more easily and extending the tests to showcase the logic the work was started by @ivanayov

Signed-off-by: Martin Dekov (VMware) mdekov@vmware.com

Description

This adds more secure experience for the user so the hmac and security validation should now be turned off intentionally with explicit false or 0

Motivation and Context

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

Actually part of #316 issue in OpenFaaS Cloud

How Has This Been Tested?

Unit tests

Types of changes

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

For derek users with authentication turned off if they move to the newest version, they should explicitly set the validate_customers: 0/false and validate_hmac:0/false

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
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.