Write Robot Inspector gradle task

[blucoat]

We had an ant script that would run Robot Inspector on each build, but now we're moving to gradle. As of right now, we just have a main method that runs the inspector, and leave it to yearly code to integrate it into the build process. A gradle task in a plugin would wrap this process up neatly for future years.

We should split out some of the OI and RobotMap code which is only used in validation and move it to a gradle plugin. This would also involve some API changes, so we should aim to get it in before 1.0.