Updating TAP reporter to specification version 13

First, this adds the functionality in #119.

Second, the "TODO" and "SKIP" reports were not implemented properly as directives.  According to the spec, directives must come after a `#` symbol.

Finally, since the YAML block can be used to describe any data structure, I moved the stack trace for errors into a multi-line string so it would be compliant with the YAML specification.

Let me know if you have any questions or if this commit needs some cleanup.

Cheers!
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