Supress the usual mime warnings from mime4j

Supress "Body part ended prematurely" and "Unexpected end of headers detected".
I believe these happens because we feed partial messages to the parser.

We've kept these logs only "just in case", but I don't think it's ever been
usueful...

Change-Id: I29e5e48abf71612eed656ce6569246caf8a320bc
1 file changed