Add HTTP/2 codec to netty-all maven dependency Motivation:

The HTTP/2 codec is missing from the netty-all maven dependency.
This means third party libraries have to pull in additional dependencies
above netty-all to use this codec.

Modifications:

Add HTTP/2 codec to netty-all

Result:

Third party libraries don't need to pull in additional dependencies
to use HTTP/2 codec.
codec-socks test cleanup

Motivation:

The unit tests in codec-socks contained redundant casts and empty test classes.

Modifications:

- Remove redundant casts
- Delete empty test classes

Result:

Cleanup