Provide Swift 4.2 runtime 🚀 about openwhisk-runtime-swift

[csantanapr]

Now that Swift 4.2 is released, we can move forward with implementing support.
@sciabarracom is looking into using the new actionloop to make swift 4.2 stateful, meaning the swift application will not exit with every invocation/run, it will read from stdin every invocation input params including env variables.

From an user perspective, no braking changes they can migrate their swift 4.1 actions to 4.2 just by recompiling and using the new epilogue based on actionloop
https://github.com/apache/incubator-openwhisk-runtime-go/tree/master/actionProxyLoop

[csantanapr]

hmm I have being tracking swift 4.2, and is about to be release but is not released yet, same for XCode 10.
https://swift.org/download/#releases

I have being holding off on doing a swift 4.2 image/kind because I wanted to buy some time to see if we could release swift 4.2 with new golang actionloop web proxy.

But if it's release before the golang web proxy is available then I guess we can get a swift:4.2 image/kind using python proxy and then later do another image/kind with golang actionloop support.

[chrislonge]

Swift 4.2 Released 🎉

[rabbah]

is this issue still relevant?

[csantanapr]

This is done