Improve support for async wiki updates. The wiki can now be properly updated in the background using Celery after a page has been edited by a user. The Flask configuration is passed on to Celery, and the background updater function is only set when running the Flask application (not when running updates via `wk`, for instance).

Flask==0.10.1
Flask-Bcrypt==0.5.2
Flask-Login==0.2.10
Flask-Script==0.5.1
Jinja2==2.7.2
Markdown==2.2.1
Pygments==1.6
SQLAlchemy==0.9.3
Whoosh==2.5.5
colorama==0.2.7
py-bcrypt==0.2
pysqlite==2.6.3
pytest==2.5.2
repoze.lru==0.6
python-hglib