trivial: not an empty list, a list of valid authentication methods
trivial: not an LOA, an unrecognized authentication method
trivial: JavaDoc test cases and name test methods
Use test method naming to express what is tested.
tests extraction works when multiple supported authentication methods
tests extraction returns null when no authn_method specified
enhance test to test that resulting service reports the expected required authentication method
tests that when service parameter missing extractor extracts null service
removes now-duplicate misplaced test
Removes a unit test that exercised the Extractor rather than the Service.  Case now tested by testMissingServiceParameterYieldsNullService .
removes duplicate misplaced tests
Removes tests of the Extractor rather than of the Service, which duplicate tests of the Extractor elsewhere.
removes test of the Extractor rather than of the Service
Extractor exercised elsewhere, including exercising this test case.
renames test case, adds JavaDoc for test case
refactor to move extraction into extractor
Refactors to move ServletRequest-touching functionality for extracting information about a MfaService into the Extractor and out of the Service implementation.
DefaultMulti…Service no longer has an opinion about `authn_method` request parameter.
Request parameter extracted and presented to the constructor already digested.
excise jsessionid from service URL in MfaService constructor
Reduces code duplication by taking advantage of inherited `cleanupUrl()` method.
Merge pull request #26 from Unicon/refactor_extractor

Refactor to do argument extraction in the argument extractor