Fix ssh-agent plugin identities comment for using multiple identities.
Add knife_ssh command to make connecting to servers managed with chef easier
No cat, and hide errors for missing cache file
Merge pull request #1981 from trobrock/knife-ssh

Add knife_ssh command to make connecting to servers managed with chef easier
Merge pull request #1980 from awidegreen/upstream

Fix ssh-agent plugin identities comment for using multiple identities.
Merge remote-tracking branch 'upstream/master'