Shares folder "New" button should be invisible

[lookacat]

Steps to reproduce

1. Go to Shares folder
2. Eg. create a new folder
3. When you try to create the folder the dialog doesn't show an error but won't work

Expected behaviour

The "New"-Button should not be visible when inside Shares folder

Actual behaviour

The "New"-Button as visible but actions wont work

[phil-davis]

owncloud/ocis#2322 reports the same problem.

IMO we are coming to the decision that oC10 and OCIS servers are going to keep behaving differently for this - oC10 let's you write you own "random" stuff to the "Shares" folder. OCIS makes the "Shares" folder a place to only receive shares.

There might be back-end server changes to help clients understand whether they cam write directly into Shares or not.

And then clients need to respond effectively to that - e.g. the web browser client here.