Removed asserts from unit tests
Fix memory issue with large return values in testcases

Previously http_SUITE:echo_body/1 and http_SUITE:check_raw_status/1
returned large values. Common test would then try to write these to the
logs causing tests to take a long time and use lots of memory.
Added range header parser
Update to 0.8.4
Update AUTHORS
Fix a small error in the REST part of the guide
Update CHANGELOG
Add diagram for rest