Return Bio-Formats version in bfCheckJavaPath()

To facilitate the debugging of users using the Matlab toolbox, `bfCheckJavaPath` now returns a second arguments with the Bio-Formats version if loci_tools.jar is loaded in the Java class path.

```
[status, version] = bfCheckJavaPath()
```

First argument is still a boolean so existing tests/functions using bfCheckJavaPath should work the same.