Fixessbt/sbt#2695
By the time the arguments are passed to a batch script,
it seems like is parsed away.
for /F did not work since it would not handle double quoted
paths that include whitespaces.
This adds special handling for -D parameters only.
Fixes#206
When I use unzipped sbt.bat it seems to runs ok, but using the msi installer version, this variable seems to expand and causes:
```
\sbt\bin\java9-rt-export.jar was unexpected at this time.
```