Improve the logs command.

Check for application's existence, and add an optional -t option, to
make it behave like "tail -f" or "heroku logs -t"
Fixed port redirection issues
Merge pull request #279 from alhafoudh/master

Fixed port redirection issues
Merge pull request #273 from plietar/logs-f

Add an option to follow the logs.
Falsy statement in installation guide.

It says:
"Almost done! For next steps on configuration:
  https://github.com/progrium/dokku#configuring"
after bootstrapping..
Merge pull request #290 from Jeewes/patch-1

Deprecated statement in installation guide.
merging upstream