Create an SBT plugin to generate client code for a project.

How to add:
Build your API generator plugin and publish locally:
> project sbtGenerator
> publish-local

For your client project:

Add JSON API file at src/main/api/[file].json

Add to project/plugins.sbt:
addSbtPlugin("sbt-apigen" % "sbt-apigen" % "1.0-SNAPSHOT")

Add to build.sbt for client project:
apiGeneratorSettings

If you are including apiGeneratorSettings in a subproject, add:
.settings(apiGeneratorSettings: _*)
Fix for quoting with Operation.pathArg where path does not start with "/"