Retrofit rx (#2519)

* Retrofit with RxJava

* Correct spelling mistake

* Use spaces for indentation instead of tabs in pom.xml

* Use spaces for indentation instead of tabs in pom.xml

* Add Retrofit integration with RxJava to libraries module

* Remove standalone project for Retrofit integration with RxJava

* remove retrofit-rxjava module

* Fixed error in pom.xml caused by an issue while merging

* Retrofit integration with RxJava

* Fix test cases

* Fix merge issues

* BAEL-1016 Merging master

libraries/src/main/java/com/baeldung/retrofit/basic/GitHubBasicApi.java

@@ -0,0 +1,33 @@
+package com.baeldung.retrofit.basic;
+
+import java.util.List;
+
+import com.baeldung.retrofit.models.Contributor;
+import com.baeldung.retrofit.models.Repository;
+
+import retrofit2.Call;
+import retrofit2.http.GET;
+import retrofit2.http.Path;
+
+public interface GitHubBasicApi {
+
+    /**
+     * List GitHub repositories of user
+     * @param user GitHub Account
+     * @return GitHub repositories
+     */
+    @GET("users/{user}/repos")
+    Call<List<Repository>> listRepos(@Path("user") String user);
+    
+    /**
+     * List Contributors of a GitHub Repository
+     * @param user GitHub Account
+     * @param repo GitHub Repository
+     * @return GitHub Repository Contributors
+     */
+    @GET("repos/{user}/{repo}/contributors")
+    Call<List<Contributor>> listRepoContributors(
+      @Path("user") String user,
+      @Path("repo") String repo);
+    
+}