* Move acme.py to acme/__init__.py to prepare splitup.
* Began moving generic code out.
* Creating backends.
* Update unit tests.
* Move remaining new code out.
* Use new interface.
* Rewrite module init code.
* Add changelog.
* Add BackendException for crypto backend errors.
* Improve / uniformize ACME error reporting.
* Create ACMELegacyAccount for backwards compatibility.
* Split up ACMEAccount into ACMEClient and ACMEAccount.
* Move get_keyauthorization into module_utils.acme.challenges.
* Improve error handling.
* Move challenge and authorization handling code into module_utils.
* Add split_identifier helper.
* Move order code into module_utils.
* Move ACME v2 certificate handling code to module_utils.
* Fix/move ACME v1 certificate retrieval to module_utils as well.
* Refactor alternate chain handling code by splitting it up into simpler functions.
* Make chain matcher creation part of backend.
Felix Fontein