normalizing shebang and bash options. also added long-term fix for bootstrap instructions
adding a DOKKU_TRACE env var to enable "set -x"
reorganizing deploy readme
Merge pull request #275 from progrium/shebang-pipefail

normalizing shebang and bash options + long-term fix for bootstrap instructions
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"