Demonstrates that qunit and loglevel are not compatible

When using qunit and loglevel, the QUnit globals for both 'log' and
'module' will prevent loglevel from operating correctly.

This problem has been discussed here:

  http://stackoverflow.com/questions/23770239/qunit-exports-global-functions

It has also been reported here:

  jquery/qunit#228

Although demonstrated with QUnit, it is generally useful for loglevel to
support customizing the logger name and correctly detect the environment
that it is running under.
Reduce false positives when detecting CommonsJS

Some environments, like QUnit, provide a 'module' object that can trick
loglevel into thinking it's running within CommonsJS.  Be more strict by
checking that module is an object, it has an exports property, and the
require function is defined.
Allow the loglevel name to be set with attributes

Provide the optional ability to set the loglevel name using attributes
on the <script> tag.  This allows loglevel to be used in environments
where the 'log' global is being used for somthing else.