Update contactcreator.php


![after patch](https://f.cloud.github.com/assets/6712989/2192736/e4932432-986d-11e3-81a8-9b41c4e3fc63.png)
![before patch_2 contacts with same alias](https://f.cloud.github.com/assets/6712989/2192738/e4eddc9c-986d-11e3-8236-c6d0c7817606.png)

 Testing for same alias is not done by Contact Creator Plugin.Due to this, 2 contacts with same alias can be created(which is not desirable). So,the extra code ,line numbers 66 to 76, appends the current time stamp to alias if the same alias is already present.
  The bug is reported at http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_id=8103&tracker_item_id=33291