Add support for bottom-<left|right|top|bottom> styles shorthands

[msamsel]

Are you reporting a feature request or a bug?

Feature request

Check if the issue is already reported

Extra notes:
IE8 automatically replace border style with set of border-top: …; border:-left: …; border-bottom: …; border-right: …; styles. That's why border shorthand conversion is not supported in IE8 at all.
Issue found during #1010.

Provide detailed reproduction steps (if any)

1. Try to add border shorthand style for table cell e.g.

<table style="width:500px">
	<tbody>
		<tr>
			<td style="border-top:2px solid red">&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

Expected result

CKEditor will replace shorthand for border-top in the same way as it is done for border

Actual result

border-top remain unchanged.

Other details

• Browser: …
• OS: …
• CKEditor version: …
• Installed CKEditor plugins: …