Fix smooth scrolling 23

[PeterGhimself]

This PR resolves #23

Summary

• fixed the error of jQuery failing in smoothscrolling,js
• fixed smoothscrolling.js
• added smoothscrolling effects to the back to top button in the footer (for every page)
• corrected a favicon.png reference (which failed to load) to favicon.ico

[PeterGhimself]

@chriskfwoo I suppose it would be a good idea, all though on some pages we have the gmaps loaded between the social media links and the footer. In any case I think it should be handled in another PR since this one is about fixing the smoothscrolling.js file.

And as for your comment on render-blocking: I like having all the scripts in one place. What if I just added an async attribute to any non-jQuery js files? Alternatively I could move it the jquery/smoothscrolling.js to the bottom of the page.. But if this render-blocking is really a problem, shouldn't we then move all the <script> tags to the bottom?

[n0pan]

I think moving the <script> tags to the bottom would be a good idea.