Merge branch '3.1.3-trash@@2' into '3.1.3'

add storagetrash interface

See merge request zstackio/zstack!3926

Merge branch '3.1.3-trash@@2' into '3.1.3'

add storagetrash interface

See merge request zstackio/zstack!3926

Update VERSION to 2.0.1

Add account resource ref for vxlan

For UI developing.

Enhance update cpu memory allocate log

add nfs-host ref to manager the connection status

add FlatDhcpUpgradeExtension

fix hostname for flat network provider when creating vm

upgrade agent version to 1.0