This refactors the `user_color_scheme_class` to use
a hash with a default.  This prevents problems
with workers that don't have access to the
current_user.

Fixes issue #2758

Simplifies some of the "active tab" checks we're doing

Merge branch 'master' into non-interactive-aws-install

Conflicts:
	doc/installation.md

Fix merge mess in installation.md

Closes #1237