analysis needed on gem dependency upgrades

[eefahy]

As seen here: https://gemnasium.com/sul-dlss/bassi_veratti this code base has 25 gems in need of upgrading and 13 open security alerts. Find easy upgrades - and document tough ones.

[atz]

Now down to 1 security alert (re: mailer, may not matter) and 11 yellow (upgradable) runtime deps.

[atz]

Now one alert (sprockets, file existence disclosure).