Add id to ProtectedBranch and BranchAccessLevel (#901)

Author: jmini

src/main/java/org/gitlab4j/api/models/BranchAccessLevel.java

@@ -4,11 +4,20 @@
 
 public class BranchAccessLevel {
 
+    private Long id;
     private AccessLevel accessLevel;
     private String accessLevelDescription;
     private Long userId;
     private Long groupId;
 
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
     public AccessLevel getAccessLevel() {
         return this.accessLevel;
     }

src/main/java/org/gitlab4j/api/models/ProtectedBranch.java

@@ -7,12 +7,21 @@
 
 public class ProtectedBranch {
 
+    private Long id;
     private String name;
     private List<BranchAccessLevel> pushAccessLevels;
     private List<BranchAccessLevel> mergeAccessLevels;
     private List<BranchAccessLevel> unprotectAccessLevels;
     private Boolean codeOwnerApprovalRequired;
 
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
     public String getName() {
         return this.name;
     }

src/test/resources/org/gitlab4j/api/protected-branch.json

@@ -1,7 +1,9 @@
 {
+  "id": 457,
   "name": "develop",
   "push_access_levels": [
     {
+      "id": 123,
       "access_level": 40,
       "access_level_description": "Masters"
     },
@@ -11,6 +13,7 @@
   ],
   "merge_access_levels": [
     {
+      "id": 789,
       "access_level": 40,
       "access_level_description": "Masters"
     },