quick frontends (app): added an "ignore_missing" argument to RemoveListener: normally an error is logged when removeListener is call on a inexisting listener, but sometimes listeners are added only in specific scenarios, and it may be handy to try to delete them without having to explictly check that they have been used.

# 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()