Rewrite rankings code to use linear regression with reference prior

This commit is a fairly major update; it changes the model for the
rankings to use OLS on the difference in score, and bases the estimates
on bayesian estimation w/ the reference prior.  The commit also tries
to make a useful caption for the ranking table.
Edit NFL standings code and text and change upload strategy

This commit adds commands to the Makefile and update to automatically generate
NFL rankings; it also makes a few changes to the caption associated with the
rankings table.  It also changes the upload strategy from email to xml-rpc
(for the standings) since wordpress doesn't handle svg through email.