nicer spinner animation

[MaxBittker]

Hello! the font awesome spinner Community uses is 8-fold symmetrical, and has a pretty nice illusion of movement when it's rotated step-wise instead of continuously (which looks kind of strange). This change just means using font awesome's fa-pulse class instead of spin. Cut and dry, except that it also means bumping our font awesome version from 4.2.1 to the latest, 4.6.2*.

Caveat: I'm currently on a train, and can't install all of the dependencies to actually test this. it should just work, but I would really appreciate if someone could check it out and give me a thumbs up 🐑

The difference between spin and pulse is demonstrated here:
http://fontawesome.io/examples/#animated

pulse was introduced in version 4.3.0
FortAwesome/Font-Awesome@89a28f8

*and font awesome follows semver, so this should theoretically not break anything!:
https://github.com/FortAwesome/Font-Awesome#versioning

https://rubygems.org/gems/font-awesome-sass/versions

Another solution would be to switch to another spinner that doesn't rely on this illusion, like fa-cog

[zachallaun]

Hey Max! Just wanted to let you know that I haven't missed or forgotten about this. Been heads-down on other dev priorities, but I hope to carve out some time for Community-related things soon.

[MaxBittker]

thanks for the note zach, this is low priority as it gets so no rush :)