Keep track of the last seen date and start crawling again from there for
the next crawl, instead of crawling everything at each invocation.
Can be configured through configuration options.
All the backend part has been rewritten to handle multiple constraints
in the config (== multiple queries).
Also did some linting.
Still to be done: frontend part and doc.
* Init Webpack / Babel / etc setup.
* Build the app using Vue, Vue-router, Vuex.
* i18n
Some backends changes were made to match the webapp development:
* Return the flat status as a single string ("new" rather than
"FlatStatus.new")
* Completely switch to calling Weboob API directly for fetching
* Use Canister for Bottle logging
* Handle merging of details dict better
* Add a WSGI script
* Keep track of duplicates
* Webserver had to be restarted to fetch external changes to the db
* Handle leboncoin module better
Also add contributions guidelines.
Closes issue #3
Closes issue #14.