Scoring of packages using pagerank, rather than user ratings

The 3-star rating of packages has historically been not very useful. Even the most well-known of packages receive even a small number of ratings from users. For example:

| Package | Number of Votes |
| ------------- | ---------------------- |
| base | 24 |
| text | 13 |
| bytestring | 11 |
| vector | 4 |

Implementing a rating system based on pagerank could help in the following ways:

1. Ratings would not be an (effectively) redundant piece of information on a package's page
2. Users could see a numerical number roughly reflective of the community's trust of the package
3. PageRank is a better fit for rating over time, since user ratings are very unlikely to be retracted/changed (or even made at all) after a changed opinion (perhaps due to an improvement in the library).

@taktoa and I discussed this and we both think this is a better approach over rule of succession/bayesian averaging/anything that relies on explicit user voting. @taktoa please comment if you have anything to add.