Since nodejs 0.10.26 (npm 1.4.3), the default when doing a `npm install --save`
is to use caret ranges (`^1.2.3`). It is now nearly impossible to use
nodejs 0.8 with recent version of libs because of this: if a transitive
dependency uses a caret, we get a "No compatible version found" error.
We can't use Travis to test nodejs 0.8: because of these dependencies,
the `npm install` phase failed.
From [here], nodejs 0.10 still has a lot of users while nodejs 0.8
doesn't even appears on the chart.