To have better control over threads, this patch adds a helper Thread
subclass which captures any exceptions occurring for later use.

Signed-off-by: Hrvoje Ribicic <riba@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>
Signed-off-by: Thomas Thrainer <thomasth@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>

(cherry picked from commit e677d5e8)