Update windows installation docs.

Merge branch/doc-updates. 

Updates Windows Installation documentation with correct node.js instructions. 
Update Core Contributor documentation to remove Ruby server information. 

@davideaster Please review, specifically Mac/Linux changes in Core Contributor section. 
Since the `get.virtual.wf` script used by the Mac and Linux installer downloads the archive from `http://download.virtualworldframework.com`, maybe we should point the Windows download there instead of requiring TortoiseGit.

We would need to copy and rename the latest Windows build and add it to the *Latest Release* section. The link to the Window .exe installer should also go away.

The current Windows .zip already contains node.js and the modules. However, the .exe (I think) generates warnings on download, so we should remove it from the new builds. The `windows-full` archive would then be similar to the Mac and Linux archives.

Here are the differences between the various 0.6.22 downloads:

### Source => Linux

* Removes content from each of the `public` demos (but leaves the directories, curiously).
* Removes `public/web`, which also removes the documentation build in `public/web/docs`.
* Adds the client build in `support/client/libz` and the Pygments `*.pyc` artifacts.
* Removes the content from `test`.

### Source => Mac

Same as Linux.

### Source => Windows

* Adds `node/node.exe`, `node/node_modules`, and `node/npm.cmd`.
* Retains `public` and adds the documentation build in `public/web/docs`.
* Adds the client build in `support/client/libz`.

### Linux/Mac => Windows

* Adds `node/node.exe`, `node/node_modules`, and `node\npm.cmd`.
* Retains `public` and adds the documentation build in `public/web/docs`.
* Has the client build in `support/client/libz` but is missing Bootstrap and jQuery that Linux/Mac includes.
* Retains `test`.

## Recommendations

* Modify the Windows build to omit the node executable and modules.
* When posting the build to `http://download.virtualworldframework.com/files`, copy `VWF_Master_...-windows-full.zip` as `VWF_Windows_latest.zip` and add it to the *Latest Release* section.
* Remove the `VWF_Windows_Install.exe` link.
* Then in the instructions here, direct the user to download the Windows build from `http://download.virtualworldframework.com`, unzip, and continue with the node.js installation, `npm install`, etc.