Added "Copy" context menu in case that selected node has imageURL.

Added "Copy" context menu in case that selected node has imageURL.

[Title] Added "Copy" context menu in case that selected node has imageURL.
[Issue#] P130517-3062
[Problem] when "SelectMode" context menu is selected after longtap on image in reader view,
          context menu(ex - Copy...) for text selection is not displayed.
[Cause] If selected node has linkURL, "Copy" context menu is added.
        In this case, selected node has only imageURL and does not has linkURL.
        So, "Copy" context menu is not added.
[Solution] Added "Copy" context menu in case that selected node has imageURL.

Change-Id: Ifedc0aa5a8b91a176653d7add6637fa9e669975b