Migrated tests to jest

Used jest-codemods to migrate, will have to pass everything by hand before we can merge.

test5/powerset/powerset.js

@@ -0,0 +1,2 @@
+const powerset = arr => arr.reduce((a, v) => a.concat(a.map(r => [v].concat(r))), [[]]);
+module.exports = powerset;

test5/powerset/powerset.test.js

@@ -0,0 +1,9 @@
+const expect = require('expect');
+const powerset = require('./powerset.js');
+
+test('Testing powerset', () => {
+  //For more information on all the methods supported by tape
+  //Please go to https://github.com/substack/tape
+  expect(typeof powerset === 'function').toBeTruthy();
+  expect(powerset([1, 2])).toEqual([[], [1], [2], [2,1]]);
+});