Run all API requests in thread pool

src/main/java/com/nutomic/syncthingandroid/http/GetTask.java

@@ -18,7 +18,7 @@ import javax.net.ssl.HttpsURLConnection;
  * Performs a GET request with no parameters to the URL in uri[0] with the path in uri[1] and
  * returns the result as a String.
  */
-public class GetTask extends RestTask<Void, Void> {
+public class GetTask extends RestTask {
 
     private static final String TAG = "GetTask";
 

src/main/java/com/nutomic/syncthingandroid/http/PollWebGuiAvailableTask.java

@@ -15,7 +15,7 @@ import javax.net.ssl.HttpsURLConnection;
 /**
  * Polls to load the web interface, until we receive http status 200.
  */
-public class PollWebGuiAvailableTask extends RestTask<Void, Void> {
+public class PollWebGuiAvailableTask extends RestTask {
 
     private static final String TAG = "PollWebGuiAvailableTask";
 

src/main/java/com/nutomic/syncthingandroid/http/PostConfigTask.java

@@ -10,7 +10,7 @@ import java.util.Collections;
 
 import javax.net.ssl.HttpsURLConnection;
 
-public class PostConfigTask extends RestTask<Void, Void> {
+public class PostConfigTask extends RestTask {
 
     private static final String TAG = "PostConfigTask";
 

src/main/java/com/nutomic/syncthingandroid/http/PostScanTask.java

@@ -10,7 +10,7 @@ import java.net.URL;
 
 import javax.net.ssl.HttpsURLConnection;
 
-public class PostScanTask extends RestTask<Void, Void> {
+public class PostScanTask extends RestTask {
 
     private static final String TAG = "PostScanTask";
 

src/main/java/com/nutomic/syncthingandroid/http/RestTask.java

@@ -35,8 +35,8 @@ import javax.net.ssl.SSLSocketFactory;
 import javax.net.ssl.TrustManager;
 import javax.net.ssl.X509TrustManager;
 
-public abstract class RestTask<Params, Progress> extends
-        AsyncTask<Params, Progress, Pair<Boolean, String>> {
+public abstract class RestTask extends
+        AsyncTask<Void, Void, Pair<Boolean, String>> {
 
     private static final String TAG = "RestTask";
 
@@ -64,6 +64,10 @@ public abstract class RestTask<Params, Progress> extends
         mListener      = listener;
     }
 
+    public void execute() {
+        super.executeOnExecutor(THREAD_POOL_EXECUTOR);
+    }
+
     protected HttpsURLConnection openConnection(Map<String, String> params) throws IOException {
         Uri.Builder uriBuilder = Uri.parse(mUrl.toString())
                 .buildUpon()