codacy: Avoid unused private fields + organize imports

src/main/java/com/owncloud/android/authentication/AccountUtils.java

@@ -36,7 +36,6 @@ import com.owncloud.android.ui.activity.ManageAccountsActivity;
 
 
 public class AccountUtils {
-    private static final String TAG = AccountUtils.class.getSimpleName();
     private static final String PREF_SELECT_OC_ACCOUNT = "select_oc_account";
 
     public static final int ACCOUNT_VERSION = 1;

src/main/java/com/owncloud/android/datamodel/FilesystemDataProvider.java

@@ -29,7 +29,6 @@ import com.owncloud.android.lib.common.utils.Log_OC;
 
 import java.io.BufferedInputStream;
 import java.io.FileInputStream;
-import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.HashSet;