#665 fix avatar query
#665 add utility methods for user list
#665 add ProgressEmptyView
#665 add AdapterView item interface and UserItemView
#665 add Participants management views
#665 add participants management sources and artefacts
#665 add conversation manager in sdk and look up existing thread for contacts based conversation when changing participants
#665 update contacts and profile picker views to use ProgressEmptyView
#665 now everything works fine
#665 add instrument test setup
#665 fix incoming contacts change conversation lookup