embedded author page pub list improvements

[eplebel]

• y-positioning of expanded key figures is way off when viewing from an embedded author page article list (example embedded author page: https://etiennelebel.com/author/harold-pashler-EMBED-AUTHOR-PAGE-from-production.html ; see this commit comment)
  - image being displayed vertically centered across entire height of iFrame, so this is a tricky one, but there's probably an ingenuous workaround! 150 points
  

• implement full-screen mode to view embedabble full-text content (PDF/HTML) within embedded author page article list 400 points (issue offering largest # of points!)

  • example: https://etiennelebel.com/author/etienne-p-lebel-EMBED-AUTHOR-PAGE-from-staging.html This page shows my author page article list (from https://curate-science-staging-2.appspot.com/app/author/etienne-p-lebel) embedded externally, using the following embed code:
    <script src="https://curate-science-staging-2.appspot.com/author-embed/etienne-p-lebel.js" async></script>
    Assuming viewport >1500px (new breakpoint), full-screen icons should be displayed to the right of any full-text links that can be displayed in an embedded fashion (see full-screen mode details #63 for more details of the specs of this feature; see https://curate-science-staging-2.appspot.com/app/author/etienne-p-lebel for working full-screen mode functionality on staging (again assuming >1900px viewport)
    

• optimize "POWERED BY" logo in embedded AP article list, so that it looks closer to spec (https://user-images.githubusercontent.com/4512335/66258992-d4dfb300-e779-11e9-9ca8-d51da29677c5.png). e.g., increase width to 75px (from 65px) and add margin-top:6px? 10 points