Add GetRules to LogicManager (#108)

## What is the goal of this PR?

We added a new LogicManager method, named GetRules, that fetches every rule in a database.

## What are the changes implemented in this PR?

Add GetRules to LogicManager

Author: Alex Walker

protobuf/logic.proto

@@ -28,13 +28,15 @@ message LogicManager {
         oneof req {
             GetRule.Req get_rule_req = 1;
             PutRule.Req put_rule_req = 2;
+            GetRules.Req get_rules_req = 3;
         }
     }
 
     message Res {
         oneof res {
             GetRule.Res get_rule_res = 1;
             PutRule.Res put_rule_res = 2;
+            GetRules.Res get_rules_res = 3;
         }
     }
 
@@ -59,6 +61,13 @@ message LogicManager {
             Rule rule = 1;
         }
     }
+
+    message GetRules {
+        message Req {}
+        message Res {
+            repeated Rule rules = 1;
+        }
+    }
 }