added initial tail call
adapted code from ssh directive to enable logs to be tailed
added tail directive to appscale executable, and set defaults for it
changed text on exception that was copypasta'd from a different method
added StrictHostkeyChecking=no to avoid asking the user if they want to log into the box
not printing stack traces for ssh and tail if the user hits Control-C
also writing locations.json file before userappserver starts, to let users ssh and tail in earlier in the deployment process
updated usage info for tail
updated from org/testing
Merge pull request #84 from shatterednirvana/appscalefile-tail

Add 'tail' command to AppScale