Transparent support LB stickiness in wAsync

[barorion]

Currently AHC doesn't carry the cookie under the hood. So to support stickiness it's needed to read the received cookie header and set it back on the Request object.

[jwcarman]

Any thoughts on this feature? For us, it's not terribly important that wAsync itself supports it, but it'd be pretty critical for the JS libraries. Is there a better work-around (some encoder/decoder or something)?