Hazard response

Update hazard service response:

• Add imt enum value with imt short label to new object
• Move xlabel and ylabel to new metadata object

Example:

{
  "response": {
    "metadata": {
      "xlabel": "",
      "ylabel": "",
      "server": {}
    },
    "hazards": [
      {
        "imt": {
          "display": "",
          "value": ""
        },
        "data": []
      }
    ]
  }
}

src/main/java/gov/usgs/earthquake/nshmp/www/meta/Parameter.java

+package gov.usgs.earthquake.nshmp.www.meta;
+
+public class Parameter {
+
+  private final String display;
+  private final String value;
+
+  public Parameter(String display, String value) {
+    this.display = display;
+    this.value = value;
+  }
+}