editing post should not change date by default

[Jens Petersen]

Currently if you edit a status post, the date stamp is changed to today by default.

It would be better to keep the date stamp unchanged from the original when editing unless a new date is explicitly given in the edited post.

[anish patil]

Added new function to edit the status message Fixed with following commit https://bitbucket.org/anish_patil/statusapp/commits/b25ec256c91f6fe83ffbd21fe811ee9daff3df05