1. Remove hostname field in DriverDevice, because agent will set
hostname together for drivers.
2. Add in_use field in DriverAttachHandle.
3. Add functions like list,create,destory for driver ovos.
4. Fix bugs of objects.
5. Remove deployable name global unique constrains.
Change-Id: I6a646a38e7c1b7042bc27465e1d912e7ff643651