Update dependencies (gems / Rails / Ruby)

[orenyk]

We're currently one minor version behind (Rails v4.1 vs Rails v4.2), but with the pending release of Rails 5 we might just want to skip ahead after a few patch updates for stability. Any thoughts?

Update 2015/11/22

I'm bundling in all of our dependency updates into this issue, including our gem dependencies, Rails (to v4.2.x), and Ruby (to v2.2.x). This is targeted for a v6.0.0 release.

Update 2015/11/30

• Update configuration documentation / Heroku buildpacks to reflect new static asset configuration variable

[orenyk]

I've started reading through the upgrade guide; there doesn't appear to be too much to change, hopefully. I think if we include an update to the Ruby version as well (while we're updating dependencies) then maybe we'll bump our next release to be a major one (e.g. v6.0.0) with all dependencies updated. Thoughts?

[orenyk]

After some more reading, this might present a problem but ties nicely into #1328, so I think that fits in with a major release as well 😄.

[orenyk]

Ok, updating Ruby didn't appear to break anything 😄. Working on Rails update now to 4.2.5 (had to update Devise simultaneously for dependency reasons).