[Altmetric](https://www.altmetric.com/) tracks social media and citation
activity for a paper. I added an option to add the altmeric id to a
paper's bib entry, which results in the altmeric badge for the paper
being displayed next to the other buttons. As an example, I added the
altmetric id for the Einstein, Podolsky & Rosen paper.
* Adds support max author limit
* typo
* fix
* display all authors by default
* Added an example
* Added 'and' before the last author
* Improve hiding/showing more authors
* Add title text
Co-authored-by: Maruan Al-Shedivat <maruan@genesistherapeutics.ai>
Co-authored-by: Maruan <alshedivat@users.noreply.github.com>
