Add dynamic list of upcoming languages
Merge pull request #1188 from pminten/elixir-forth-exercise

Add Elixir forth exercise
Roughly organize views
Fix broken link
Merge pull request #1190 from slava-sh/master

Fix broken link
Simplify space age example. Fixes #190
Add a couple of database indices
Collapse db migrations
Avoid Code.eval_quoted in elixir dot-dsl

This turns out not to be needed.
Merge pull request #1191 from pminten/elixir-dot-dsl-improvement

Avoid Code.eval_quoted in elixir dot-dsl
Don't use newrelic in console
Add migration for user exercises.

Each submission for a language/slug belongs to an exercise. That hasn't
been explicit in the data model until now.
Write to (as yet unused) user exercise.
Update user exercise column on submission
Actually link user exercises and submissions
Optimize user exercise data migration
Tweak user exercise data migration
Don't use newrelic in rake tasks
Save language/slug on user exercise
Add index to user exercise