The actions to run synchronously can be configured via the `execute_sync`
configuration key.
Executing an action synchronously means that SFTPGo will not return a result
code to the client until your hook have completed its execution.
Fixes#409
ioutil is deprecated in Go 1.16 and SFTPGo is an application, not
a library, we have no reason to keep compatibility with old Go
versions.
Go 1.16 fix some cifs related issues too.
The common package defines the interfaces that a protocol must implement
and contain code that can be shared among supported protocols.
This way should be easier to support new protocols
