Use relative paths for redirects

[plannigan]

Changes the path assigned to location.href to be relative to old html page.

The PR adds pytest test cases to verify the produced paths.

You can also see the output in action. These are the configured redirects.

Using relative paths:
Fixes #17 (Local file redirects)
Fixes jimporter/mike#35 (Site hosted in a sub-directory without depending on a static site_url from the mkdocs config)

[plannigan]

@burkestar @zhimsel Would it be possible to get a review of these changes?

[zhimsel]

I no longer have write access to the repo as I no longer work at DataRobot.

[prcr]

I ran into the same issue of mkdocs-redirects not being compatible with mike.

Right now I'm already using the solution from this pull request in production:

codacy/docs@4ee1d2e

Here are the resulting changes to the redirect pages:

codacy/docs@fc03c3b

And here's the an example URL that correctly redirects to the target page:

https://docs.codacy.com/v2.0.387-deprecated/hc/en-us/articles/207278449/

[prcr]

@burkestar, how can we work to have these changes merged into the original project?

[burkestar]

Thanks @plannigan for the contribution here, and @prcr for the reminder.

I'll get this released to PyPI today. Needs a changelog update and possibly a few other tweaks to get it ready. Sorry for the long delay!

[burkestar]

Released as 1.0.2

[prcr]

Thanks for the quick reply @burkestar! 👍

I began doing a full rollout of the new version of the plugin to production but came across an issue in the specific scenario of having a redirect target index.md (as I'm doing to redirect a few deleted pages to the documentation homepage). I proposed a simple fix on #21.