Reject the package upload if the README download fails (#473)
Reject the package upload if the README download fails (#473)

- Return an error if the README download fails
- Log README failures to MixPanel
quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt