Code review comment for lp:~alecu/ubuntuone-client/capt-nemos-share-hand

To test this:
 * compile and install the nautilus plugin in this branch, as per the instructions in: https://wiki.canonical.com/UbuntuOne/CodeReviewFaq#ubuntuone-client%20Nautilus%20Plugin
 * restart nautilus: killall nautilus
 * right click on a folder that has been uploaded to Ubuntu One, and select "Ubuntu One" -> "Share..."
 * select an email from the list or add a new email address and use it
 * immediately after you click on the "Share" button a share emblem should show up on the folder (it looks like an orange and a green arrow)
 * now try right clicking on that folder and going to the "Ubuntu One" menu. The "Stop Sharing" option should be grayed out, because there's no webservice call to cancel share offers, only accepted share offers (bug #752986).