quick frontend(widgets): added QuickWidget.target property as a helper method to get a single target: a single target is the most common case, but QuickWidget handle multiple targets. When a single target is requested and multiple exist, a random one is returned. This is a temporary situation, targetting should be improved in a future version to manage multiple targets in hash.

# XXX: the Monkey Patch is here and not in src/__init__ to avoir issues with pyjamas compilation
# TODO: remove this when changes are merged in Wokkel
from sat_tmp.wokkel import install
install()