CMS-1571 Refactoring: Move some admin packages

Moved the following packages in modules/wem-web package:

    Moved com.enonic.wem.web.json.* to com.enonic.wem.admin.json.*
    Moved com.enonic.wem.web.rest.* to com.enonic.wem.admin.rest.*
Merge pull request #211 from enonic/CMS-1571

CMS-1571 Refactoring: Move some admin packages