Add license.

Closes #58.
Merge pull request #60 from wting/wting_58_add_license

Add license.
Simplify test_app() settings.
Manually test response status code.
Merge pull request #62 from wting/wting_fix_silently_failing_tests

Fix silently passing tests
Add clean makefile target.
Add file encoding declarations.
Minor cleanup.
Use namedtuple for settings.
Do not error if path is missing and validation disabled.

Fixes #57.