Delete leading zero from fragment timestamp

The current timestamp in the ConversationFragment dateFormatter is in AM/PM format. It would most likely be expected therefore that there would not be a zero padding on the hour for this time.

This change removes the zero padding from the hour in the dateFormatter so that instead of "09:12:45 pm", the representation would now be "9:12:44 pm".

Format documented here:
http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html#number