merging website docs into brooklyn docs, with versioned things (the content wot woz here) into "guide"

completed, i think

@rdowner can you have a look now?  i know there's a lot, but mostly dumb stuff, updating brooklyncentral links and download links

when done i think we want to:

* merge https://github.com/apache/incubator-brooklyn-site/pull/18
* request https://github.com/apache/incubator-brooklyn-site/pull/19 be applied to brooklyn (btw we had two brooklyn.properties, this is now fixed)
* DONE - install latest version w snapshot docs into svn
* DONE - install old versions into svn
* DONE - brooklyncentral.github.com html page should redirect to brooklyn.io
* request deletion of incubator-brooklyn-site on github

(update: i didn't mean to push svn site but i forgot svn ci is git ci plus git push :( -- it's going live, still uploading but should be finished soon)