Test: add a standalone tool which process content

This tool is a simple main class which can be used to test what is extracted from a given binary file or from its base64 equivalent.

You can give as first argument the BASE64 content

Available options:

 -u file:/URL/TO/YOUR/DOC (in place of BASE64 content)
 -s set extracted size (default to mapper attachment size)

Examples:

```
StandaloneTest BASE64Text
StandaloneTest BASE64Text -s 1000000
StandaloneTest -u /tmp/mydoc.pdf
StandaloneTest -u /tmp/mydoc.pdf -s 1000000
```

Closes #89.