Add new “log” rpc call.

This permits the client (Ode) code to log messages on the server
side.

Change-Id: Id91ac3d4f814fb352ab2d42c84bcb86e098642f5
Detect Truncated Blocks Files when they are written.

Offer the user to opportunity to either continue or abort the session
(this will do a window reload).

Change-Id: I7066993e2fae2d3e10d4026f201216374afb196f