When WOPI's CheckFileInfo or GetFile responds with status code other
than HTTP 200, show a message to the user indicating some problem in the
storage.
Currently, we open an empty document if storage doesn't return a
document which surely is not correct.
Mention the storage server address when asking user to contact the
server administrator to be more friendly.
Change-Id: I15f0489f36db8689b43d42f6b691fdd21815e4fa
We can calculate the timeout ourselves easily and add it to the
polling loop simplifying life.
Also ensure we never send messages to a non-authenticated thread.