Update inspect.lua

Allow passing the option `excludeMeta` to blindly skip printing the metatable info like `inspect(t, {excludeMeta=true})`. This is useful for printing clean debug information on things like higher-level 'data type' wrappers. Ie - printing the contents of a python dict-like object

```lua
function dict:keys()
  local keys = _.keys(self.__items__)
  setmetatable(keys, {
    __tostring = function()
      return inspect(keys, {excludeMeta=true})
    end
  })
  return keys
end
```