Update roslibjs to advertise Services

[chris-smith]

Updates roslib so that it can advertise services in addition to calling them.

Example Usage

let addTwoInts = new roslib.Service({
    ros: rosConn,
    name: '/add_two_ints',
    serviceType: 'beginner_tutorials/AddTwoInts'
});

addTwoInts.advertise((req, resp) => {
    resp.sum = req.a + req.b
    return true;
});

[rctoris]

👍

[reinzor]

👍