Fixed pos medias URL

following this pull request:
Afrozaar@9e4ae39

Fix/Fixed bug in media fetch - was not separating postId and context params correctly Afrozaar#75

Author: Chaiavi

src/main/java/com/afrozaar/wordpress/wpapi/v2/request/Request.java

@@ -30,7 +30,7 @@ public abstract class Request {
     public static final String TAXONOMY = "/taxonomies/{slug}";
     public static final String TERMS = "/terms/{taxonomySlug}";
     public static final String TERM = "/terms/{taxonomySlug}/{termId}";
-    public static final String POST_MEDIAS = "/media?parent={postId}?context={context}";
+    public static final String POST_MEDIAS = "/media?parent={postId}&context={context}";
     public static final String MEDIAS = "/media";
     public static final String MEDIA = "/media/{mediaId}";
     public static final String PAGES = "/pages";