Upgrade Confluence to use Atlassian Core 3.11

This is actually a "Good Thing", since it will uncover an old bug in Confluence. This being a runtime dependency on Webwork1 .... nice.

Atlassian Core 3.11 has removed all webwork1 dependencies, this helps out in a few areas, including the weird POM errors with Maven that you may of been getting in IDEA. e.g. WTF is webwork1 doing on my classpath!

I have assigned this the MattJ since he is working with some of the Velocity stuff at the moment and this will actually be the area where the error will occur, yep there is webwork1 dependent class in your velocity context... nice