Write a TAP v12 formatter

[schwernbot]

From: @schwern Date: Thursday Nov 17, 2011 at 06:57 GMT Orig: https://github.com/Test-More/test-more/issues/219

Write Test::Builder2::Formatter::TAP::v12.

The only current difference between this and v13 is it does not output the TAP version header.

The basic tasks are:

• Move the TAP::v13 code into its own file, probably TAP::Base. Leave TB2::Formatter::TAP as a factory.
• TAP::v13 defaults show_tap_version to true.
• TAP::v12 defaults show_tap_version to false.

New contributors, please see https://github.com/schwern/test-more/wiki/Preferred-workflow for general information about working with this project.