Add list of keyCodes

Excuse me if this has been already discussed and I missed it. But, have you considered listing the keyCodes in here before? It's used by our sibling projects [UI](https://github.com/jquery/jquery-ui/blob/master/ui/jquery.ui.core.js#L22) and [Mobile](https://github.com/jquery/jquery-mobile/blob/master/js/jquery.mobile.core.js#L101). If so, this commit adds the unified-unique-keys from both projects.

Perhaps the downsize would be the extra bits below.

```
 raw     gz Compared to master @ 18cccd04a6f69018242bce96ef905bc5d3be6ff8
+514   +323 dist/jquery.js
+381   +317 dist/jquery.min.js
```

In percentage.
```
 raw     gz Compared to master @ 18cccd04a6f69018242bce96ef905bc5d3be6ff8
+0.21%   +0.45% dist/jquery.js
+0.45%   +1.08% dist/jquery.min.js
```