Tests fail on Windows due to DIRECTORY_SEPARATOR
colliding with namespace delimiter and its normalization logic...
so, just settle on literal forward slash for directory separator,
since PHP on Windows can still handle that correctly in file paths;
'global' subdir was missing, as implied by the
addNamespace('\\', '/path/to/global/includes') line later on;
add test to find a file in the 'global' namespace;
a global namespace registered as '\\' is ignored by current logic;
provide a means to check it if it has been registered;
Spec itself precludes the ability to register "\\",
so remove references that imply it is allowed;
Merge pull request #167 from ashnazg/psr4-tests

Tests fail on Windows;  Registered Global Namespace unreachable