use 'response' to send 'NoSuchKey' when local file is not found
log FS delete errors only on failure
execute success callback when filesystem copyfile completed
change copy test to match usage in web, check http status
check delete status code in copy test
update unit tests - FileHandler now calls deleteDirectory on cache directory
test against rimraf module when deleting directory recursively
fix getFileStream unit test as callback no longer fires immediately

success callback is now called only when file is readable