Affected Issue(s): #606 (#612)

What this commit has achieved:
1. Externalized location of "mdm-rules.json" in the `AppProperties`
2. More info about the `ResourceLoader` interface is available at
https://docs.spring.io/spring-framework/reference/core/resources.html#resources-resourceloader

src/main/java/ca/uhn/fhir/jpa/starter/AppProperties.java

@@ -27,6 +27,7 @@ public class AppProperties {
   private Boolean ips_enabled = false;
   private Boolean openapi_enabled = false;
   private Boolean mdm_enabled = false;
+  private String mdm_rules_json_location = "mdm-rules.json";
   private boolean advanced_lucene_indexing = false;
   private boolean enable_index_of_type = false;
   private Boolean allow_cascading_deletes = false;
@@ -191,7 +192,15 @@ public class AppProperties {
     this.mdm_enabled = mdm_enabled;
   }
 
-  public Cors getCors() {
+  public String getMdm_rules_json_location() {
+	return mdm_rules_json_location;
+}
+
+public void setMdm_rules_json_location(String mdm_rules_json_location) {
+	this.mdm_rules_json_location = mdm_rules_json_location;
+}
+
+public Cors getCors() {
     return cors;
   }