adding new apis requested from gluster-swift proj

This patch adds new functions that are used in gluster-swift.
These functions are: dup, lseek, getatime, getctime, getmtime

Change-Id: I09036f7e393a89e09913f7f6de173e1eca8dca95
Signed-off-by: Thiago da Silva <thiago@redhat.com>