Pass arguments to `tail`

https://devcenter.heroku.com/articles/logging

If you have multiple dynos and/or dyno types and want to filter log tailing to
the process or dyno type, you pass those filters on with the `--source` or
`--ps` arguments. This commit adds argument passthrough to the `tail` command.
Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.