Registry for P2PXWiki name resolution

Implement a registry for p2pxwiki name resolution.

There is a central registry for name resolution. The central registry allows for the wiki names to be distinguishable. Also it helps in solving the problem of wiki-hijacking.

• extension: central registry can be replicated between a set of servers
• extension: central registry functionality can be handed by peers. There will be a need for ensuring the integrity of the registry data in this case.

More on this in the design issues section http://www.xwiki.org/xwiki/bin/view/Dev/Design+Issues