Support running Clojure nodes from LFE

[oubiwann]

This has previously been done in an ad hoc manner, and we need to make it easy for developers to start Clojure nodes from LFE using methodologies familiar to Clojure developers. We'll start with support for lein and the assumption of a lein-based Clojure project, but we can extend that to boot and raw java later. Maybe even maven.

Features required in Clojang to support this effort:

• Add new behaviour defining functions for working with JVM-based OTP nodes
• Add new behaviour implementation for managing lein-based nodes
• Add new behaviour implementation for managing nodes via .jar file
• Release a new version of Clojang with these features

Related tasks in the lfecljapp project:

• Update the LFE code to start the Clojure server node using the new API created above - #

Part of release #20 (0.4.0)