Spinner override

When using `./oab-java6` in a Vagrant shell provisioner each cycle of the spinner is printed to a new line resulting in a pretty useless print-out of

```
/
-
\
|
```

down your entire screen. This simple change allows the user to override the spinner string, effectively disabling it by setting it to a blank string.

For example:
```
[sudo] SPINNER="" ./oab-java.sh
```