Execute tests on Node.js 11 in CI

[kibertoad]

Currently it is unclear whether grpc-node actually supports Node.js 11; tests in CI would clarify that.

[sangaman]

I'm unable to install grpc-node in travis builds using Node 11, so it would be good to know whether it's supported or whether there's something wrong with the build.

[nicolasnoble]

grpc depends on node-pre-gyp for its binary releases and builds, and node 11 support depends on node-pre-gyp node 11 support. Follow #593 for node 11 integration, which is blocked on node-pre-gyp.

[julien-c]

If this is happening at every node release (which it is, in my experience), maybe a good idea would be to test upcoming releases in advance?

[nicolasnoble]

This isn't about us being proactive. This is about our dependency having to update their code so we can even do testing.

[julien-c]

Got it (did not mean to sound abrasive too)

[nicolasnoble]

Also, @sangaman, if you are unable to install grpc with node 11, please make a full report. The installation is supposed to fallback on building from sources, and from what we know, it's working fine for us when we trigger this installation mechanism.