Show/Hide delete and upload buttons according to writable status of the share

[csoni111]

The /shares response JSON contains the list of shares visible to the user along with their writable status. The writable field denotes if that share is writable or not for the logged-in user. Client app must appropriately display/hide the Upload or Delete button as per the value of the writable field for a given share.

Ref: https://github.com/amahi/amahi-anywhere-specs#shares