Move global.instances creation to node_vwf.js, so that it is available as soon as the server starts

Refs #2886
Remove unused global.activeinstances variable

Refs #2886
Merge remote-tracking branch 'remotes/origin/development' into branch/nodejs-500-error

Conflicts:
	node_vwf.js
Merge pull request #97 from virtual-world-framework/branch/nodejs-500-error

Branch/nodejs 500 error

Fixes #2886