Removed unnecessary imports.
Moved views.py, update statistics are stored in the database.

views.py moved to views/core.py. Submodule will allow to better organise them.
Added Update model for storing update statistics.
archive_chan_update command saves the statistics in the database.
Added status view. Added api views.
Added basic information to the status page.
Added chart to the status page.
Added a command importing update logs to the database.
Chart can be zoomed in.
Last updates are shown on the status page.
Warning: boards that have never been updated are not displayed.
Added link to status to the footer.
Fixed potential bugs in the scraper.
Increased accuracy of statistics in thread mode.
Statistics JS will now recover from errors.
Rescaled charts.
Merge branch 'dev-status' into dev
Denormalized the thread model.
Added database triggers.
ThradScraper split into separate functions.
Removed aggregation in board view.
Removed now redundant code from admin.py.
Moved the code around in models.
get_absolute_url is used in templates, added mixins to views to clean up the code.
Added command which allows to recount the data in the thread model.
Removed redundant imports.
Added a way to override default global MEDIA_URL.
Fixed status chart scale.