Migrated tests to jest

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

test6/tail/tail.js

@@ -0,0 +1,2 @@
+const tail = arr => (arr.length > 1 ? arr.slice(1) : arr);
+module.exports = tail;

test6/tail/tail.test.js

@@ -0,0 +1,10 @@
+const expect = require('expect');
+const tail = require('./tail.js');
+
+test('Testing tail', () => {
+  //For more information on all the methods supported by tape
+  //Please go to https://github.com/substack/tape
+  expect(typeof tail === 'function').toBeTruthy();
+  expect(tail([1, 2, 3])).toEqual([2, 3]);
+  expect(tail([1])).toEqual([1]);
+});