feat(page): add PageType to Page model

this commit add a PageType enum containing supported type for writing
documentations like MD, SWAGGER, etc

Breaking changes:
- type attribute in Page.java is now of type PageType

src/main/java/io/gravitee/repository/management/model/Page.java

@@ -30,7 +30,7 @@ public class Page {
 
 	private String name;
 
-	private String type;
+	private PageType type;
 
 	private String content;
 
@@ -57,7 +57,7 @@ public void setId(String id) {
 		this.id = id;
 	}
 
-	public String getType() {
+	public PageType getType() {
 		return type;
 	}
 
@@ -69,7 +69,7 @@ public void setName(String name) {
 		this.name = name;
 	}
 
-	public void setType(String type) {
+	public void setType(PageType type) {
 		this.type = type;
 	}
 

src/main/java/io/gravitee/repository/management/model/PageType.java

@@ -0,0 +1,14 @@
+package io.gravitee.repository.management.model;
+
+/**
+ * @author Ludovic Dussart (ludovic.dussart at gmail.com)
+ * Managed types for page documentation
+ *
+ */
+public enum PageType {
+
+	MARKDOWN,
+	RAML,
+	SWAGGER
+
+}