Stop testing Node 4, explicitly test React 16
Stop testing Node 4, explicitly test React 16

Node 4 is EOL and should not be used anymore. This removes it from
the test suite so that we can speed things up a bit.

I've also started explicitly resting React 16, rather than rely
on the fact that our devDependencies have React 16.

I've also made explicit testing against at least React 0.14.9,
since we don't support versions of React below that, and since
it is pre-major version, npm will treat feature versions as
major versions.

Further, this also uses the newest version of npm to do our
install which should speed things up a bit. npm version is
independent of Node version so this should have no impact other
than speedier installs.

brigade/react-waypoint,brigade/react-waypoint