Update angular-locker.js

This way `locker.get('notExists', false)` will return `false` instead of `undefined`.

Before:
 * `locker.get('notExists', false)` would return `undefined`
 * `locker.get('notExists', 0)` would return`undefined`
 * `locker.get('notExists', null)` would return `undefined`
 * `locker.get('notExists', '')` would return `undefined`
 * `locker.get('notExists', NaN)` would return `undefined`

Now:
 * `locker.get('notExists', false)` returns `false`
 * `locker.get('notExists', 0)` returns`0`
 * `locker.get('notExists', null)` returns `null`
 * `locker.get('notExists', '')` returns `''`
 * `locker.get('notExists', NaN)` returns `NaN`