Migrate to new Sheets v4 api

This moves us from the oudated google/data XML api to the OnePlatform REST/JSON api, finally silencing the deprecation warnings we've been seeing.

The synchronization algorithm diffs the spreadsheet's current values with its internally sourced values, adding the row to a batch update request if there's a discrepancy. Additional internal data are added as an append operation to the end of the sheet, and any extraneous spreadsheet data is cleared from the spreadsheet.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=169273590

java/google/registry/export/sheet/SyncRegistrarsSheetAction.java

@@ -28,7 +28,6 @@ import com.google.appengine.api.modules.ModulesServiceFactory;
 import com.google.appengine.api.taskqueue.TaskHandle;
 import com.google.appengine.api.taskqueue.TaskOptions.Method;
 import com.google.common.base.Optional;
-import com.google.gdata.util.ServiceException;
 import google.registry.config.RegistryConfig.Config;
 import google.registry.request.Action;
 import google.registry.request.Parameter;
@@ -133,6 +132,7 @@ public class SyncRegistrarsSheetAction implements Runnable {
         return;
       }
     }
+
     String sheetLockName = String.format("%s: %s", LOCK_NAME, sheetId.get());
     Callable<Void> runner = new Callable<Void>() {
       @Nullable
@@ -141,7 +141,7 @@ public class SyncRegistrarsSheetAction implements Runnable {
         try {
           syncRegistrarsSheet.run(sheetId.get());
           Result.OK.send(response, null);
-        } catch (IOException | ServiceException e) {
+        } catch (IOException e) {
           Result.FAILED.send(response, e);
         }
         return null;