build-scripts: fixed bug
build-scripts: fixed bug

Now files are deleted before build is executed. Else all output is simply
concatnated to existing files.

CCLDESTY/xml3d.js,CCLDESTY/xml3d.js,xml3d/xml3d.js,xml3d/xml3d.js,ariyapour/xml3d.js,Fiware/webui.Xml3d.js,ariyapour/xml3d.js,Fiware/webui.Xml3d.js