Added HTTPFromURIAsyncGetter, RestHelper, ChatHelper.
HTTPFromURIAsyncGetter is async task for getting data from given URI - should be used only for GET rest reuests.
IHTTPFromURIAsyncGetterResultTarget is interface for classes that should be notified when HTTPFromURIAsyncGetter is done.
RestHelper contains RestAPI related constants + example json responses.
ChatHelper is underlaying class of chat view.

Signed-off-by: Krtek <qwetek@gmail.com>