Define __copy__ and __deepcopy__ as identity functions on DomainSpecificString, so that copy.deepcopy() will work on them

Create a placeholder for each image of the chat thread. The height of this placeholder is the height of the image so that the scroller position will not be disrupted when the image will be actually loaded and displayed in its full height

In case of image message, the body can be a JSON object (ImageInfo) and ngSanitize does not like that (ie it generates exception in the console)

Added registration/login jsfiddle, formatted so it can be loaded directly from jsfiddle. Requires jQuery 1.8.3

Conflicts:
	tests/rest/test_presence.py
	tests/rest/test_rooms.py
	tests/utils.py

on method calls to be made later