Fixed sftp-server put verb not working. Tested from out sftp client and
linux fedora openssh 6.9p1 sftp clients in transferring small and large
files using both get and put verbs.
sftp-server.exe code modified to work in Windows as NoMachine never
finished it to work. I/O handling to work as a subsystem and
openssh7.1p1 sshbuf_new() buffer system code had to be used. sshd_config
file need location of sftp subsystem to be specified.