jp (blog/preview): fixed watch restoring when file is moved/deleted: with some editors (e.g. vim), when file is written it is actually replaced with a buffered one. In this case, jp replace the watch to check the new file, but it was not working anymore with latest version of inotify module. This patch fixes it by removing the old watch before adding a new one.

# 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()