New endpoint to return data for complaints.

app/complaint/complaint_rest.py

@@ -0,0 +1,16 @@
+from flask import Blueprint, jsonify
+from sqlalchemy import desc
+
+from app.errors import register_errors
+from app.models import Complaint
+
+complaint_blueprint = Blueprint('complaint', __name__, url_prefix='/complaint')
+
+register_errors(complaint_blueprint)
+
+
+@complaint_blueprint.route('', methods=['GET'])
+def get_all_complaints():
+    complaints = Complaint.query.order_by(desc(Complaint.created_at)).all()
+
+    return jsonify([x.serialize() for x in complaints]), 200