Fixed EZP-20293: OE removes enters in IE9 if XML block contains a table

JIRA: https://jira.ez.no/browse/EZP-20293

# Description

This issue affects only Online Editor 5.3 when it is used with IE9. Basically, if Online Editor has to handle a `table` in a paragraph, ie something like:

```html
<p>Test</p><p>Test</p><p><table><tr><td>Table</tr></td></table></p>
```

it will enclose the whole code in a `div`, this breaks the logic of the OE parsers (client side/server side) and as a result news lines are transformed/stored as `br` by TinyMCE and our eZ XML parser removes new lines.

This patch makes sure the `table` in paragraph situation does not happen client side and server side. The client side part is inspired by the code in the table plugin.

Newer versions of TinyMCE handle this correctly hence why I don't plan to put any part of this in master.

# Tests

Manual tests in IE9, IE8, Firefox 20 and Chrome