#insertComment(): Allow comments to be added

[eddiemonge]

I know the goal of this is to programmatically control the Gruntfile but users will still probably read it to understand whats going on. Without the ability to add comments, it is hard to know exactly what is going on. Each method should take an optional comment parameter that is added before whatever is being added to the GF.

There should also be a way to add pure comments that don't have supporting code like:

// Generated on #{date()} for #{name}

Hard part is to determine where to insert the comments I think