Allow Array.prototype Augmenting

[mkantor]

This plugin had problems when Array.prototype was augmented (something done by many JavaScript shims, e.g. es5-shim and Augment.js).

My solution was to use $.each instead of for...in iteration in several places, which is smarter about avoiding properties from array prototypes.

Here's a quick test:

• v2.4 (notice the property value is present in the generated CSS)
• with my changes

I also bumped the version number to 2.5.

[codler]

Thank you!!