Whitespace fix

This PR updates mustache.js to the latest version (#119) while also fixing the recently discovered issue relating to whitespace being dropped (#145).

The mustache.js implementation has been customized again to keep the HTML escaping mechanism the same. For example, where `title` equals `<&>`;

```
> {title}
<%>
> {{title}}
&lt;&amp;%gt;
```

However, due to the update, this can also be done via the following;

```
> {&title}
&lt;&amp;%gt;
```

The guide intro **_still_** needs to be updated to cover this approach. Other than that, I just want to perform some additional testing before this PR can be merged in to v1.2.1.