Modify procfile

Instead of running `lemmad` using `.profile.d`, run it as a child process by inserting `bin/lemmad` into the `Procfile`'s `web` process type definition.

Works on my staging app, not surprised if this can be cleaned up :)
the meat of it is from [shoreman](https://github.com/hecticjeff/shoreman/blob/master/shoreman.sh#L74-L87).

Are you sure there aren't edge cases being handled by this that wouldn't be handled by an awk one-liner? Note all the test cases in that project.