Support higher-order tasks and aliases that use trampolines in lein.bat

lein.bat had a separate code path for commands that started `lein trampoline ...`
I have removed this and made all cases set `TRAMPOLINE_FILE`, so that things like this alias work:

```clojure
{"dumbrepl" ["trampoline" "run" "-m" "clojure.main"]}
```

Also tweaked the handling of double quotes for `JAVA_CMD`, they were getting doubled in my last patch (though this didn't seem to break anything).