Figure out why deployment with Ruby 2.2.3 doesn't work

[orenyk]

We've been unable to run Reservations on Yale VMs with Ruby 2.2.3 installed (e.g. for v6.x); everything installs correctly but Passenger won't start properly. Manually switching to Ruby 2.1.2 (by editing the Gemfile and .ruby-version) works. This is likely just an infrastructure thing but we need to figure it out and resolve it (and possibly test it on a DO droplet as we did in #1074 to smoke test).

[orenyk]

Testing this on DO now.

[orenyk]

This has taken FOREVER, jeez. Hack-y systems administration is not ideal...

[orenyk]

Ok, everything worked on DO so we'll have to see what's broken specifically with our ITS setup.