This makes it much easier to see why a test is failing. Before, a
`helper.waitFor()` failure would simply cause the test to time out.
Now an exception is displayed.
These changes make the frontend tests send keydown instead of keypress in
firefox, in accordance with #3413 (Use keydown instead of keypress on Firefox).
The percentage of passing frontend in Firefox 61 on this revision is 100%.
Currently pressing ENTER on a line that ends with ':', '[', '(' or '{'
automaticaly indents the new line with 4 spaces. The variable added by
this commit to settings.json allow an Etherpad instance to not have this
behavior.
Richard Hansen