Consolidate lua utils & attribute sources

[AdamWagner]

There are four different files with lua utils in /utils, which is completely unnecessary.

• /utils/utils.lua
• /utils/underscore.lua
• /utils/table-utils.lua
• /utils/flatten.lua

Worse, several of these are copied straight out of an active repo, without attribution!

[AdamWagner]

Closed by: #20