Make the redirect check more precise

HTTP 304 (Not Modified) and 305 (Use Proxy) are not redirects so
they should probably not get the "redirects not allowed" error
message.

Not sure about 300 (Multiple Choices), but I left it out as well.
Merge pull request #8 from fmarier/redirect_check

Make the redirect check more precise
use blanket for coverage, inline instrumentation ftw
remove uneeded includes
improved handling of sloppy secondaries support documents
changes in 0.0.4
bump to 0.0.5 after publishing 0.0.4
allow over-riding of principal in client testing tool
changes in 0.0.5
ver bump after publishing 0.0.5
improved error message
sloppy support document test case is more wholistic - tests from assertion rather than lookup in isolation: this verifies that parameters are passed along from verification to lookup
fix issue with fallback being forgotten - pass along arguments - always.
changes in 0.0.6
use ass to check code coverage during test run
move to dev version of jwcrypto
email addresses set as 'sub', new format support
changelog and version bump to 0.0.7
augment testing libraries, allow client to control whether email is present as 'sub' key
changelog and 0.0.8 version