extractVersion should work for x.y version formats

[tarekrached]

presto's non-semantic versioning (currently 0.148) doesn't work with the current extractVersion()

here's a test case:

    it("works with super basic versions", () => {
      expect(External.extractVersion('0.1')).to.equal('0.1');
    });

[vogievetsky]

Huh... Alternatively Presto's version could be made semantic by appending ".0" to the end. Thoughts @tarekrached

[tarekrached]

this is somewhat moot, as I can't figure out how to introspect the presto version, so this is all kind of made up anyway :)