Missing Env NODE_MAX_INSTANCES & NODE_MAX_SESSION for NodeDebug images

[niQo]

as done in #295 , it wil be usefull to have the same environment variables in the NodeDebug images (NodeFirefoxDebug & NodeChromeDebug)

[diemol]

@niQo The NodeDebug images are created based on the NodeBase images, therefore those env vars are included by default.

[niQo]

@diemol you're right, it has been done. This issue can be closed.