This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Minor fixes to add Rails 6 support to Discourse, we now will boot
with RAILS_MASTER=1, all specs pass
Only one tiny deprecation left
Largest change was the way ActiveModel:Errors changed interface a
bit but there is a simple backwards compat way of working it
