Remove unused key uploadedfiles

Change-Id: I5b1b4b5a706c2670b855d2b514bdf9ebd90c10b0
Update documentation for used message keys in Special:Emailuser

These had been tucked away uncomfortably :(.

Change-Id: I1b387751722d944de8a50d31ce14595c80f65f54
Merge "Update documentation for used message keys in Special:Emailuser"
Merge "Remove unused key uploadedfiles"