Blocking Params, Relative Root, Better Log Tailing

New

• blocking_params option to prevent multiple messages with the same param values from running at the same time with thanks to @skarip.
• relative_root option to mount RQ at a non-root web path.
• Better log tailing and checkbox to tail or not to tail stdio.log.

Changes

• The coalesce = yes / no and coalesce_paramN = 1 / 0 options are replaced with coalesce_params = [1, 2, 3] in queue configs. This matches the new blocking_params option.
• Various UI tweaks and improvements.
• Various code cleanups.