Test error on long filenames in AUTOREFRESH mode
Test error on long filenames in AUTOREFRESH mode

Requests will very long paths can trigger `OSError: [Errno 36] File name
too long` when in AUTOREFRESH mode, as raised in issue #110. The correct
response is for WhiteNoise to ignore such requests and pass them
straight through to the application.

This patch adds a test for this behaviour.

evansd/whitenoise,evansd/whitenoise,evansd/whitenoise