issue0024-merge-process

1. merge transfer to deepin-dwonload-service
2. call transfer directly instead of by dbus
3. mv "transfer/ftp" to "ftp"
4. load dbus in daemon instead of func init()

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/56a2ba17be5c4c0684690f99fbc0ef62/

Change-Id: I3b2d07ea91fad91d0aeb9a6dcfbf2d9adfeae07b