restruct xio_session

Split xio_session.c to 3 files xio_session_server.c for
server specific code and xio_session_client for client
specific code. Common code is left in xio_session.c
A private header file xio_session_priv.h was added and
it contains the prototypes of the fuctions which are
private to the session "class". (static in one file implementation)

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
rename two connection routines

Rename xio_send_connection_hello_{req|rsp} to
xio_connection_send_hello_{req|rsp}.
This is according to all other connection send routines.

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
Event loop was exiting while the wakeup event is still in the epoll
when running the loop again, the epoll exit immidiatly.

Signed-off-by: Eyal Salomon <esalomon@mellanox.com>
second session does not change state after connect

Signed-off-by: Eyal Salomon <esalomon@mellanox.com>
Performence improvments

Signed-off-by: Eyal Salomon <esalomon@mellanox.com>