Merge pull request #5 from fponticelli/master

lazy loading of modules
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Merge pull request #7 from AxGord/master

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Added Sys.exit, Check node version before accessing #Immediate

setImmediate/clearImmediate aren't available for Node < 0.9,
in this case setImmediate and clearImmediate are left undefined.
Merge pull request #8 from deltaluca/master

Added Sys.exit, Check node version before accessing #Immediate
merged upstream