Fixed REST API typo

    ➜  ~  curl -X POST -H "Accept: application/json" -H "Content-Type: application/json" \
      localdocker:8080/v2/apps -d '
    {
        "id": "hello",
        "cpus": "0.1",
        "mem": "32",
        "cmd": "echo hello; sleep 10"
    }'
    {"message":"JsResultException(errors:List((/cpus,List(ValidationError(error.expected.jsnumber,WrappedArray()))), (/mem,List(ValidationError(error.expected.jsnumber,WrappedArray())))))"}%

---

    ➜  ~  curl -X POST -H "Accept: application/json" -H "Content-Type: application/json" \
      localdocker:8080/v2/apps -d '
    {
        "id": "hello",
        "cpus": 0.1,
        "mem": 32,
        "cmd": "echo hello; sleep 10"
    }'
    {"id":"/hello","cmd":"echo hello; sleep 10","args":null,"user":null,"env":{},"instances":1,"cpus":0.1,"mem":32.0,"disk":0.0,"executor":"","constraints":[],"uris":[],"storeUrls":[],"ports":[],"requirePorts":false,"backoffSeconds":1,"backoffFactor":1.15,"container":null,"healthChecks":[],"dependencies":[],"upgradeStrategy":{"minimumHealthCapacity":1.0},"version":"2014-12-18T15:01:55.913Z"}%