Added ComputerName to Get-SSHSession
Added ComputerName to Get-SSHSession

Added the ability to find all sshsession with a specific
ComputerName/Hostname to Get-SSHSession.  Made "Index" the default
ParameterSetName so no existing scripts should break.

darkoperator/Posh-SSH,tomlarse/Posh-SSH,bgshacklett/Posh-SSH