Improve error scoping

[mskelton]

Fixes #113

Improves error message scoping so that errors are less obtrusive and more accurate to the problem. See the before/after screenshots below for a preview of what this changes in the output.

This makes it significantly easier to both find the actual issue as well as not overwhelm users. I noticed it was very distracting with test.skip causing the entire test to show as errored when I really only want it to show on the .skip portion of the test.

Most of this change is adding validation to test to ensure the error messages are at the proper location. The changes to the source rules in most cases was just changing node to node.callee in the context.report method.

Before

After