change rspec output format to nested

I make this change locally like 3 times a week, if nobody objects, I'll
just make it permanent.

Change-Id: Ic825cc94fe8bfc8d3ef2044e91a59cfb2c6f0446
Reviewed-on: https://gerrit.instructure.com/4751
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: JT Olds <jt@instructure.com>

Author: codekitchen

spec/spec.opts

@@ -1,3 +1,3 @@
 --colour
---format progress
+--format nested
 --format html:tmp/spec_html/index.html