Show only one 'Copy collection' button per collection (Bug #1314020)

When going to Portfolio -> Collections -> Copy a collection the 'Copy
collection' button only shows once per collection now.

When going to Portfolio -> Pages -> Copy a page the 'Copy
collection' button shows for each page in a collection still.

Change-Id: Ia742744f6c9fff0c93c0eeb1ed4c353c28a60b88
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
Merge "Show only one 'Copy collection' button per collection (Bug #1314020)"