add method to return all versions

src/main/java/gov/usgs/earthquake/nshmp/www/HazVersion.java

@@ -3,9 +3,19 @@ package gov.usgs.earthquake.nshmp.www;
 import com.google.common.io.Resources;
 
 import gov.usgs.earthquake.nshmp.internal.AppVersion;
+import gov.usgs.earthquake.nshmp.internal.LibVersion;
 
 public class HazVersion implements AppVersion {
 
+  public static VersionInfo[] appVersions() {
+    VersionInfo[] versions = {
+      new HazVersion().getVersionInfo(),
+      new LibVersion().getVersionInfo(),
+      new WsUtilsVersion().getVersionInfo(),
+    };
+    return versions;
+  }
+
   public VersionInfo getVersionInfo() {
     var resource = Resources.getResource("version/nshmp-haz-version.json");
     return AppVersion.versionInfo(resource);