allow hidden remote git url

I have a usage scenario where I'd like to customize the displayed version information by the buildpack and hide the remote git url.

For comparison, here is the sample output of the default behavior where version.yml hasn't been provided
```
-----> Java Buildpack Version: 6d68606 | git@github.com:spaungam/java-buildpack.git#6d68606
```
Here is a sample of a customized `version.yml` with the intention to hide the remote git url:
```
version: '1234'
remote: ''
hash: ''
```

Resulting output of the displayed version information with the customized `version.yml`:
```
-----> Java Buildpack Version: 1234 | #
```

As you can see, there's the unwanted characters `|` and `#`.  This merge request is an adjustment on the version processing to only append these characters if there is a non-empty remote/hash string value.  When the remote/hash string is empty, the desired output is:
```
-----> Java Buildpack Version: 1234
```