Added PR for BackToTop proposal

[fsgiudice]

@rstoenescu
Hi just added my first PR with a little component “Back To Top”.
Please check it and eval if it can be useful
Francesco

[fsgiudice]

Hi @rstoenescu,
I saw you commit about this PR. Very good.
I was thinking about to generalize a bit more this directive calling it “v-scroll-to” so you can use it in more ways:

1. scroll to top
2. scroll to an object position (like menu item, or to next page, think to paginate full screen vertically)
3. scroll to bottom

Using DOM id or other reference.
What do you think?
Francesco

[rstoenescu]

@fsgiudice I like the ideas!