Changed lingering external_authzfn strings to external_authz_callable.
Merge pull request #22 from syngin/master

Changed lingering external_authzfn strings to external_authz_callable.
fix travis test run by using tox==1.6.1 version
fix pep8 violations in talons.auth
Merge pull request #23 from swistakm/fix/minor-auth-pep8-fixes

fix pep8 violations in talons.auth
Merge pull request #24 from swistakm/fix/tox-tests-issue

fix travis test run by using tox==1.6.1 version
Add Mel Boyce and Michal Jaworski to AUTHORS in prep for 0.2 release
Change error message to reference new conf

The old external.Authenticator's external_authfn configuration option is
now called external_authn_callable, but the error messages on bad
configuration still referred to the old config name.
Merge pull request #27 from jaypipes/authfn-config

Change error message to reference new conf
Allow callable conf options to be callables

The external_authn_callable and external_authz_callable configuration
options only accepted strings, in 'module.function' form. This patch
adds the ability to simply supply an actual callable as the value of
these config options.
Merge pull request #28 from jaypipes/authfn-config

Allow callable conf options to be callables
Merge pull request #30 from jaypipes/issue29

Fix Issue #29 - Handle http_auth of None