fix for error 500 on /discover path

TypeError: Cannot read property 'contentType' of undefined
    at /var/www/epc/api/node_modules/connect-rest/lib/connect-rest.js:58:41
    at Route.maction (/var/www/epc/api/node_modules/connect-rest/lib/route.js:11:3)
    at /var/www/epc/api/node_modules/async/lib/async.js:594:23
    at /var/www/epc/api/node_modules/async/lib/async.js:548:21
    at /var/www/epc/api/node_modules/async/lib/async.js:224:13
    at iterate (/var/www/epc/api/node_modules/async/lib/async.js:131:13)
    at async.eachSeries (/var/www/epc/api/node_modules/async/lib/async.js:147:9)
    at _asyncMap (/var/www/epc/api/node_modules/async/lib/async.js:223:9)
    at Object.mapSeries (/var/www/epc/api/node_modules/async/lib/async.js:213:23)
    at Object.async.series (/var/www/epc/api/node_modules/async/lib/async.js:546:19)