title: error in adding google play services as reference library in eclipse
body: <p>1>  When i add google play services library it shows <strong>green right</strong> mark but when i press ok and reopen      project properties its showing <strong>red cross</strong> mark.</p>
  
  <p>2> In eclipse when i create new android project it by default creating activity which  ActionBarActivity insted of Activity. Why?</p>
  
  <pre><code>public class MainActivity extends ActionBarActivity {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      if (savedInstanceState == null) {
          getSupportFragmentManager().beginTransaction()
                  .add(R.id.container, new PlaceholderFragment()).commit();
      }
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
  
      // Inflate the menu; this adds items to the action bar if it is present.
      getMenuInflater().inflate(R.menu.main, menu);
      return true;
  }
  </code></pre>