updated miniExclude to point to the renamed 'tests' directory

'grunt build' is failing on a fresh install: 
...
Building Dojo...
>> Error
Warning: Task "dojo:dist" failed. Use --force to continue.
...
from the build log:
...
error(307) Failed to evaluate module tagged as pure AMD (fell back to processing with regular expressions).
	module: dojogen/tests/dojoConfig; error: ReferenceError: location is not defined

Due to the directory name change on the last commit, tests are now added to the built version. I've updated the miniExclude resource to reflect the directory name change.