Add white shade when FAB is expanded

This updates the floatingactionbutton to the newest version (master tree) and uses the newly introduced OnFloatingActionsMenuUpdateListener to create a white shade when the floating menu is expanded.
When the shade is touched, the menu is closed.
The Java code for the ConversationLayout class is as following:
```Java
package ninja.vextil;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.RelativeLayout;
import com.getbase.floatingactionbutton.FloatingActionsMenu;

public class ConversationsLayout extends RelativeLayout {
    View mOverlay;
    FloatingActionsMenu mFABMenu;
    public ConversationsLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public void onFinishInflate() {
        mOverlay = getChildAt(1);
        mOverlay.setOnTouchListener(new OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                mFABMenu.collapse();
                return true;
            }
        });
        mFABMenu = (FloatingActionsMenu)getChildAt(2);
        mFABMenu.setOnFloatingActionsMenuUpdateListener(new FloatingActionsMenu.OnFloatingActionsMenuUpdateListener() {
            @Override
            public void onMenuExpanded() {
                mOverlay.setVisibility(View.VISIBLE);
                mOverlay.animate().alpha(1).setDuration(500);
            }

            @Override
            public void onMenuCollapsed() {
                mOverlay.animate().alpha(0).setDuration(500).withEndAction(new Runnable() {
                    @Override
                    public void run() {
                        mOverlay.setVisibility(View.GONE);
                    }
                });
            }
        });
    }
}
```