Add option for stricter javascript checks

[jorrit]

Currently, the target test is added to my Modernizr build because I have the following code:
e.target
In this case, I am just reading the target of an event, it has nothing to do with Modernizr. Customizr detects this test because it checks for .target in my Javascript file. I always use Modernizr.<test>, so I would like to request an option to only detect tests when they directly reference Modernizr. This prevents false positives.

[jenssimon]

+1