Add "ssh-add" command
Add "ssh-add" command

Add "ssh-add" command for agent forwarding to work.
skynet/docs,coreos/docs,jdloft/docs,ksmaheshkumar/docs-2,jonboulle/docs,iankronquist/docs,marineam/coreos-docs,endocode/coreos-docs,michelleN/docs,hkjn/docs-1,bq-xiao/docs,ionave/docs,wli6/docs,mjg59/docs,atxwebs/docs,mischief/coreos-docs,joshix/docs,robszumski/docs