Pysaml2

- Add preferred signing and digest algorithms configuration options:
Use the new configuration options `signing_algorithm` and `digest_algorithm`.
- Fix signed SAML AuthnRequest and Response when HTTP-Redirect binding is used:
Previously, the query params `Signature` and `SigAlg` were not included.
- Ignore duplicate RequestedAttribute entries when filtering attributes
- tests: Avoid reuse of old test data files

- Fix extraction of RegistrationInfo when no information is available
- Fix http_info struct to include status-code

- Allow to specify policy configurations based on the registration authority.
- Add new configuration option `logout_responses_signed` to sign logout responses.
- When available and appropriate return the ResponseLocation along with the Location
attribute.
- Always use base64.encodebytes; base64.encodestring has been dropped.
- Examples: fix IdP example that was outputing debug statements on stdout that became
part of its metadata.
- CI/CD: Use Ubuntu bionic as the host to run the CI/CD process.
- CI/CD: Pre-releases are now available on [test.pypi.org][pypi.test.pysaml2]. Each
commit/merge on the master branch autotically creates a new pre-release. To install a
prelease, run:

sh
$ pip install -U -i https://test.pypi.org/simple --extra-index-url https://pypi.org/simple pysaml2


[pypi.test.pysaml2]: https://test.pypi.org/project/pysaml2/#history

- Fix the generated xsd:ID format for EncryptedData and EncryptedKey elements
- Set the default value for the NameFormat attribute to unspecified when parsing
- Support arbitrary entity attributes
- Replace all asserts with proper checks
- Allow request signing in artifact2message
- Support logging configuration through the python logger
- Fix wrong identifiers for ecdsa algos
- Fix automatic inversion of attribute map files
- Factor out common codepaths in attribute_converter
- Remove uneeded exception logging
- Docs: Update configuration options documentation
- Examples: Support both str and bytes in SAML requests on the example idp
- Examples: Update to key generation to 2048 bits

- Fix signed logout requests flag

- Differentiate between metadata NameIDFormat and AuthnRequest NameIDPolicy Format
- Users using `name_id_format` to set the `<NameIDPolicy Format="...">` attribute now
need to use the new configuration option `name_id_policy_format`.
- Fix documentation formatting