Adding support for conditional client libs in VersionedClientlibsTransfo...

The VersionClientLibrary transformer currently does not support client libs which are placed inside conditional statements. e.g.
```
<!--[if lte IE 9]>
    <cq:includeClientLib css="myproject.ie"/>
<![endif]-->
```
Can you pull `Pattern.compile(..)` out to be a static var so the Pattern compilation only happens once? (as Pattern compilation is expensive)