add dav4droid support part1

src/com/owncloud/android/lib/common/operations/RemoteOperation.java

@@ -39,6 +39,8 @@ import com.owncloud.android.lib.common.utils.Log_OC;
 
 import java.io.IOException;
 
+import okhttp3.OkHttpClient;
+
 
 /**
  * Operation which execution involves one or several interactions with an ownCloud server.
@@ -77,6 +79,11 @@ public abstract class RemoteOperation implements Runnable {
      */
     private OwnCloudClient mClient = null;
 
+    /**
+     * Object to interact with the remote server
+     */
+    private OkHttpClient mHttpClient = null;
+
     /**
      * Callback object to notify about the execution of the remote operation
      */
@@ -142,6 +149,25 @@ public abstract class RemoteOperation implements Runnable {
         return runOperation();
     }
 
+    /**
+     * Synchronously executes the remote operation
+     *
+     * Do not call this method from the main thread.
+     *
+     * @param client Client object to reach an ownCloud server during the execution of
+     *               the operation.
+     * @return Result of the operation.
+     */
+    public RemoteOperationResult execute(OkHttpClient client, Context context) {
+        if (client == null)
+            throw new IllegalArgumentException("Trying to execute a remote operation with a NULL " +
+                    "OwnCloudClient");
+        mHttpClient = client;
+        mContext = context;
+
+        return runOperation();
+    }
+
 
     /**
      * Asynchronously executes the remote operation