AttachError() method add a new context to Logger with key
`attached_error` as the keyword to contribute with the best practices
when using the log package.
HH-111
Adds log, slugify, herror and test packages initially created for
Hungry Hippo project. This also includes a Makefile to help testing
all packages, consolidate coverage report, exame Go source and ensure
format, a gitlab-cy.yml file.
HH-86