Add custom attribute to published output

[chrta]

Fixes #455

No tests and no documentation added, since this follows the suggestion in #455.

My questions:

1. Is this approach ok, or should this be implemented in a different way?
2. What kind of tests should be added?
3. Where should the documentation be added?

[chrta]

@jacebrowning Would this be something that could be merged after adding missing doc and tests? Can you provide some feedback?

[jacebrowning]

@chrta Thanks for getting this started! In order see how this feature will work, can you add another TUT item with some custom attributes configured to be published? Here's what the TUT document looks like currently: https://doorstop-pr-476.herokuapp.com/TUT.html

[jacebrowning]

Thanks for adding that!

Perhaps the attributes table should only be displayed if there are one or more rows in it?

[jacebrowning]

Thanks, I like way that published HTML looks! Are you able to rebase on the upstream develop? I think that will fix the deployment failure.

Comment: The tests fail for me (also on my local pc on the develop branch) because of some issue with plantuml.

Would you mind opening a separate issue for this? Maybe someone else can help out!

[chrta]

Comment: The tests fail for me (also on my local pc on the develop branch) because of some issue with plantuml.

Would you mind opening a separate issue for this? Maybe someone else can help out!

Sorry, this was an issue when i opened this pr in May, this works now. I will remove this from the initial comment.

Also rebased to current develop.

[jacebrowning]

Thanks!

[jacebrowning]

This functionality is available in a beta release: https://pypi.org/project/doorstop/2.2b4/