Abstracted device-list refresh.
Abstracted device-list item-click-listener (new class
DeviceListItemClickListener).
Abstracted device-manager frontend device-observer (new class
FrontendDeviceObserver).

Main-activity is almost 150 lines shorter now :). This was not possible
before, due to generics.
Merge branch 'master' of https://github.com/madeentje/allshare_demo.git

Conflicts:
	src/dimitri/suls/allshare/gui/activities/Main.java
	src/dimitri/suls/allshare/managers/device/DeviceManager.java