Provide better defaults for OwlLoadTask

[mprather]

User Story

Building a gradle build file is tedious.

Based on observations across multiple projects, all projects typically take the output from the OwlReason task as input. If issue #37 is picked up, this would be a similar change for the OwlLoadTask.

The goal is to simplify the amount of gradle code that needs to be stamped out for what is a common pattern.

Detailed Description

Two changes suggested:

1. Remove iris as a required parameter.
2. Provide default values that represent the following:

    iris           = [
        "$namespace/bundle/classes",
        "$namespace/bundle/properties",
        "$namespace/bundle/individuals"
    ]