compress sqlite on server and download/uncompress locally to speed up download times 

```
> file.size("25a6546ba3c2_annotationhub.sqlite3")
[1] 121782272
> tar("25a6546ba3c2_annotationhub.sqlite3.tar.xz", "25a6546ba3c2_annotationhub.sqlite3", compression  = "xz")
> file.size("25a6546ba3c2_annotationhub.sqlite3.tar.xz")
[1] 6672412
> untar("25a6546ba3c2_annotationhub.sqlite3.tar.xz", exdir = tempfile()) |> system.time()
   user  system elapsed
  0.722   0.042   0.782
```
