Fix gemify (again)

Continued from https://github.com/focuslight/focuslight/pull/26. Fixed to execute `focuslight start` in the gem. 

Problems:

1. See https://gist.github.com/chiastolite/9246215. This was caused because `Dir.pwd` will be changed to the gem directory in the Foreman scope. So, `.env` in the `focuslight new` directory was not read on execution of `focuslight longer` and `focuslight shorter`. 
1. In addition, `bundle exec unicorn -E production -p $PORT -o $HOST` tries to read `config.ru` on the command execution directory, i.e., `focuslight new` directory which did not exist before. 

How to resolve the problems:

* To relolve the both problem, I generated `Procfile` and `config.ru` files in addition to `.env` by `focuslight new` command. 

Please notice that the procedure was changed like:

```
 focuslight new
+cd focuslight
 focuslight init
 focuslight start
```

And, we now can use `bundle exec focuslight start` command on git-cloned directory, too.