Added unit test for Segment::getOffset(). It can reproduce Steve's off by 1 error.
Added unit test for Segment::getOffset().
It can reproduce Steve's off by 1 error.

utah-scs/RAMCloud,utah-scs/RAMCloud,anirajk/RAMCloud,SMatsushi/RAMCloud,anirajk/RAMCloud,anirajk/RAMCloud,anirajk/RAMCloud,jblomer/ramcloud,utah-scs/RAMCloud,utah-scs/RAMCloud,SMatsushi/RAMCloud,anirajk/RAMCloud,utah-scs/RAMCloud,jblomer/ramcloud,jblomer/ramcloud,SMatsushi/RAMCloud,anirajk/RAMCloud,jblomer/ramcloud,jblomer/ramcloud,SMatsushi/RAMCloud,SMatsushi/RAMCloud,utah-scs/RAMCloud,SMatsushi/RAMCloud,jblomer/ramcloud