Node-Flowdock doesn't work in Node 7

[pimterry]

In Node 7, process.EventEmitter doesn't exist (and in Node 6 it's deprecated, and will print a warning), but Session here extends it. See nodejs/node#6862 for more details.

It'd be nice if the engines field in node-flowdock's package.json caught this, but it'd be even better if this worked. You could plausibly move to const EventEmitter = process.EventEmitter || require('events').EventEmitter if you want to keep backwards compatibility too.