support generic less config - closes #13

[yomed]

Added config.lessConfig, some brief documentation, and a test case to demonstrate it working with strictMath. I looked at testing some other configuration too, but those are less obvious to test, so I left them out for now. I brought in lodash to extend the parseConfig object. Let me know of any changes if needed.

[patrick-steele-idem]

Thanks @yomed. New version published: lasso-less@2.1.2

I did remove the usage of lodash only because it was not needed. raptor-util was already a dependency and it provides the same method.

Thanks again.