Cpplint and avoid using namespace

update/agent/include/agent/linux/datasid-agent.h

update/agent/include/agent/linux/datasid-common.h

update/agent/include/agent/linux/datasid-conf.h

update/agent/include/agent/linux/datasid-parse.h

update/agent/include/agent/linux/datasid-proxy.h

update/agent/include/agent/main.h

update/agent/src/linux/datasid-agent.cpp

update/agent/src/linux/datasid-common.cpp

update/agent/src/linux/datasid-conf.cpp

update/agent/src/linux/datasid-parse.cpp

update/agent/src/linux/datasid-proxy.cpp

update/agent/src/main.cpp