Don't consider WordPress too old if no $wp_version

When testing WordPress is loaded in a function and
the version globals aren't globals.

This is a workaround until they're fixed in core:
http://core.trac.wordpress.org/ticket/17749#comment:40
Travis the liveblog tests

* Move the phpunit config to the root dir
* Make bootstra.php depend on the env variable
and deprecate the bootstrap-sample.php
* Many thanks to @scribu and his wp-cli plugin tests
scaffold!