Fix problems with spaces in path names under windows

[tillsc]

Avoid IllegalArgumentException from new URI(...) by using getRawSchemeSpecificPart() to preserve correct escaping (e.g., for spaces in Program Files).
This occurred for example when running java -jar "my_app.war" -S rake -T under windows.

I left this.path unchanged because it's unclear what other parts of the code expect there.
Instead, I extract a separate pathWithoutMain for URI construction.