[Ovmsdev] Please update mongoose submodule

[Stephen Casner]

I have changed the mongoose mg_send() function to return the number of
bytes appended or zero if buffer allocation fails.  The code in
console_ssh now depends upon this to avoid corrupting the ssh packet
stream if the system runs low on free memory.

Thus, if you update the the latest OVMS master branch, please remember
to "git submodule update" as well.

                                                        -- Steve