ADded meaintenance placeholder page

ADded meaintenance placeholder page.

    .gitftpignore
    maintenance/background.png        (+)
    maintenance/background_repeat.png (+)
    maintenance/base.css              (+)
    maintenance/down-page.html        (+)
    maintenance/layout.css            (+)
    maintenance/skeleton.css          (+)
    maintenance/style.css             (+)
    maintenance/swl_logo_sm_light.png (+)