- designed a contact list item for the contact list view
- added a list view to the ContactListActivity layout
  -implemented an onClickListener for the list view
- added a debug button to test notification behaviour
- implemented notification behaviour as user hopefully would expect (still unfinished, is a lot of work)
- added an alert dialog to notify the user about a declined position request
- implemented an adapter for the contact list view (ContactListAdapter)
- added functionality to the map activity to handle position requests
- implemented functionality to update the user presences via the RosterListener
- map activity will be "finished" when stopped (e.g. home button pressed or display switched off)
- changed the PositionRequestDialogFragment to a yes/no dialog (when dialog is canceled it will be taken as a "no"/rejection of the request)
Merge remote-tracking branch 'origin/master'

Conflicts:
	app/src/main/java/com/example/fmi_fmf/ContactListActivity.java
	app/src/main/java/com/example/fmi_fmf/FMFCommunicationService.java
	app/src/main/res/layout/activity_contact_list.xml
	app/src/main/res/values/strings.xml