Upgrade async-http-client to 2.0.x

[jeffpeiyt]

Make a version that is compatible with eBay/parallec#37

[jeffpeiyt]

Seems the SslContext needs to use the netty one, which only supports pem but does not support JKS file anymore. Need more changes to adept to this change
netty/netty@1c588ce

[jeffpeiyt]

netty/netty#5888 (comment) this helps

[jeffpeiyt]

released as https://oss.sonatype.org/content/repositories/snapshots/io/parallec/parallec-plugin-http-clientauth/0.20.0-SNAPSHOT/