use string-resource with placeholder instead of hardcoded concatenation

as this is more l10n/translation friendly

Change-Id: I1050fb24e0d6e94a2f1ad1605003a9c7010ca7cb

android/source/res/values/strings.xml

@@ -122,7 +122,7 @@
     <string name="search_label">Go</string>
     <string name="directory_browser_label">Choose Directory</string>
     <string name="bad_directory">Invalid directory path</string>
-    <string name="current_dir">Current Directory:</string>
+    <string name="current_dir">Current Directory: %1$s</string>
 
     <!-- Save Alert dialog strings -->
     <string name="save_alert_dialog_title">Save the document before closing?</string>

android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java

@@ -473,8 +473,8 @@ public class LibreOfficeUIActivity extends AppCompatActivity implements Settings
             findViewById(R.id.header_recents).setVisibility((View.GONE));
             actionBar.setTitle(dir.getName());
             findViewById(R.id.text_directory_path).setVisibility(View.VISIBLE);
-            ((TextView)findViewById(R.id.text_directory_path)).setText(getString(R.string.current_dir) +
-                    " " + dir.getUri().getPath());
+            ((TextView)findViewById(R.id.text_directory_path)).setText(getString(R.string.current_dir,
+                    dir.getUri().getPath()));
         }
 
         new AsyncTask<IFile, Void, Void>() {