Update 3rd party licenses

Since we no longer ship a gemcache, this removes references to the
gemcache.  I still list all 3rd party gems for convenience.
Revert "Revert "Land #2505" to resolve new rspec fails"

This reverts commit e7d3206dc9d153fe7867fb6c7764620273f9faf3.
Blow away remnants of Local::Unix
Missed an errant require

Wasn't even using it anyway
Land #2607, reverted reverted merge fix for #2505
Land #2605, update LICENSE for reality.