Use the disco.compat.http_server to work with python3.
Make the passed arguments to sysctlbyname convertible to c_char_p.

In python3, the default type of strings are unicode which cannot be
converted to c_char_p, resulting a type error from sysctlbyname,
using a b prefix for the string makes it convertible to c_char_p.
Clean up the test_chunked_http.

This commit has no functional effects.
Use byte string in test_chunked_http to comply with python3.
Simplify the join_done method in test_query.
Remove the unused util directory.

The files in this directory are quite out of date and unnecessary now.
Use str_to_bytes in the test_raw_pipeline to comply python3.
Remove the deprecated data_err, err, and msg functions.
Change test_trans to comply with python3.
Convert bytes and strings to each other to work with python3.

With this commit, test_save should pass on python3.
Add some items to the release notes of 0.5.
Merge pull request #431 from pooya/shayan/python3

Shayan/python3