Add uuid to iproto greeting

src/CMakeLists.txt

src/box/applier.cc

src/box/iproto.cc

src/box/lua/net_box.lua

src/box/xrow.cc

src/box/xrow.h

src/trivia/util.h

test/box/net.box.result

test/unit/CMakeLists.txt

test/unit/xrow.cc

test/unit/xrow.result