Add duScrollDelay option for smoothScroll directive

[homerjam]

This is useful when you have an additional click event bound to the same element as the smoothScroll directive that should trigger an event before triggering the scroll.

[oblador]

Thanks for your PR @homerjam!

Wouldn't it make more sense to have the other click handlers to invoke the smooth scroll via scrollToElementAnimated() in that case? Don't want to unnecessarily bloat the API and configs.

[homerjam]

Well yes that's an option of course, but I personally thought the bloat was worth it in this case.

No problem if you don't want to include it though. I can make a custom directive derived from yours to use in my projects.

Thanks for the great module anyway!

[oblador]

I think it's an edge case that pretty easily can be done in another way that's why :-) Leaving this PR open for a while to see if anybody else has any need for it.

[homerjam]

Good plan, consider me a +1 : )