Button tags should not use default link behaviour

[mikemartin]

Fixes issue where {{ partial:components/button as="button" label="My button" }} would inherit the default href attribute.

Changes proposed in this pull request:

• Add condition to avoid default 'href' attribute for button tags.

[robdekort]

Looks good. Thanks Mike. We should probably move this to the tools addon so it can easily be updated. 🤔