update-ssh: Remove phpseclib, use ssh2 functions

[momoss]

Definition Of Done

Q	A
Added Specs	-
Review and 2 GTM	Ok
Micro Demo to the PO (Story only)	-

Todo: Pending / Work in progress OK: Done / Validated -: Not needed

[ahocquard]

@anaelChardan SFTP usage is not a good idea: we are replacing it by ssh +scp. Either use ssh + scp or use sftp if it fulfil your needs. Not both. As ssh is more powerful than sftp (mysqldump, etc), we will only use it.

[anaelChardan]

ok @ahocquard ;)