support actionloop language runtimes

Supporting the openwhisk [actionloop](https://github.com/apache/openwhisk/blob/master/docs/actions-actionloop.md) runtimes in a generic way could add debug support for multiple languages automatically and natively (without the user having to set extra arguments on the wskdebug cli). This _might_ need some small changes in the various runtimes, ie. knowledge of the debug mode and port of the particular language or execution environment.

[Previous discussion](https://lists.apache.org/thread.html/rc1bfe107c5014109d5c9be8936f8a26496bb5ced3ec457eb10cab486%40%3Cdev.openwhisk.apache.org%3E).