I am installing a new service in an outbuilding, It is not at my residence so I can't test it readily. On the neutral/grounding bars in the panel, it appears as if the neutral and ground are all connected. In fact, on both bars, there are 2 screws for ground/neutral. To clear this up, on older panels the screws are right underneath each other. On this panel, there are 2 screws, space, 2 screws. this is what makes me think the ground and neutral can be on the same bar. The panel box is from Lowe' and I think it might be called Homelite.
Since this has its own meter, it's its own service entrance, but put a ground bar in anyway
Since you're getting a separately metered drop from the utility (instead of running a feeder from another building on the property), it's a service entrance all its own, so a service bond between neutral and ground needs to be established here. (In other words, the green screw or strap that makes the neutral-to-ground connection stays put.)
I would still get a ground bar (Square-D PK15GTAL) and install it in the panel, then land the grounds separately from the neutrals, though, as this makes converting the panel to run off a feeder at a later date rather easier. (Having two services on the property can get...awkward if you want control of say outdoor lights from both buildings.)
If this is your main service panel both neutral and ground are connected and the ground and neutral buds are interchangeable or usable for both equipment grounds (bare or green wire) and the white or neutral are the same at only this point. If this is a sub panel fed from a main someplace else on the service the ground and neutral busses must be isolated per code.