Fix for Javadoc Warnings

Seeing the below warnings from ALS Rest JavaDocs:
```
11 warnings
[WARNING] Javadoc Warnings
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Because.java:53: warning - Tag @link: reference not found: Response.Status#NOT_FOUND
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/MostSurprising.java:55: warning - Tag @link: reference not found: Response.Status#NOT_FOUND
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#OK
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#SERVICE_UNAVAILABLE
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Recommend.java:64: warning - Tag @link: reference not found: Response.Status#NOT_FOUND
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#OK
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#SERVICE_UNAVAILABLE
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#OK
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#SERVICE_UNAVAILABLE
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#OK
[WARNING] /Users/smarthi/oryx/oryx-ml-oryx-serving/src/main/java/com/cloudera/oryx/ml/serving/als/Ready.java:29: warning - Tag @link: reference not found: Response.Status#SERVICE_UNAVAILABLE
```