Add new Bad Request Error type

When handling rest api's it's helpful to have a bad request error type that returns a 400 error code as described here:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/400

This release adds this functionality.

v0.23.4

Log failurs in ready server checks

v0.23.3

• Fix race condition in key broker

v0.23.0

• Improved middleware/metricsmw package and make sure histograms and counters are registered automatically.
• Deprecate register method in middleware/metricsmw
• Fix a whole bunch of spelling mistakes across the entire project.
• Improve the README example to include HTTP middlewares.