Better username in commit metadata

[samoht]

Currently, the Git history in pinata looks like this:

commit 7be99481c37abb6a4d92a3686d72491c793af810
Merge: 390f6e1 390f6e1
Author: irmin9p <[email protected]>
Date:   Mon Feb 29 10:56:34 2016 +0000

    (no commit message)

commit 390f6e1b55ab3e7f0b5aaaff9b1d33c779d5d933
Merge: 4209536 4209536
Author: irmin9p <[email protected]>
Date:   Mon Feb 29 10:56:31 2016 +0000

    (no commit message)

Would be great to make this a bit more useful...

[talex5]

This should be on pinata I think... DataKit provides a msg file to set the commit message but pinata doesn't use it yet. /cc @djs55

(I guess usernames will come with #11)