GRAILS-11351 handle -D parameter with whitespaces

This fixes the issue that command line parameter with whitespaces are handled the wrong way.

`grails "-DghprbPullTitle=Title with spaces" clean`
grails fails with this error message

    Script 'With' not found, did you mean:
    1) IntegrateWith
    2) Init
    3) CreateUnitTest

Maybe this is a bit *the easy way* fixing this issue. Hope this helps to fix this issue soon :)