Refactoring multiple lua modules into luaPackages

Please, feel free to contest.
>> +    lua51only = true;
>
>This will become soon a problem in the long-term. What about `disabled = lua.luaversion != "5.1";` or such (pythonPackages do something similar).

Not even long term: 
We have Lua 5.1 5.2 5.2-compat LuaJIT, and Lua 5.3 (probably in -compat
and -nocompat versions, like 5.2) is coming soon…