Implement homepage design from mockups

[eporter23]

The following document summarizes some ideas and feedback during discussions with SCO:
https://docs.google.com/drawings/d/1E7F43DRTN-gLS8HgmYMoqc5IA21guuIzl2N47QGQG24/edit?usp=sharing

One major change is the removal of the "Recently Uploaded" section.

Also, see this high-res wireframe that brings in some ideas shown in the above document. Please feel free to expand and enhance the ideas shown here. It also brings in more actual content detail including collection titles and descriptions, etc. to better show layout considerations.