Takes an allowed set of keys and filters out all other key/values pairs.
const { Objectfilter } = require('objectfilterer')
let obj = {
a: 1,
b: 2,
c: 3,
d: 4
}
let allowed = ['a', 'c']
let filtered = Objectfilter(obj, allowed) // expects { a: 1, c: 3 }