More consistent name for collection icons storage

More consistent storage names (only with underscores, no dash)

We don't need anymore ADDON_ICON_BASE_URL

We are still in py2.6

We don't need anymore ADDON_ICONS_DEFAULT_URL

Consistent way for string formatting

PREVIEW_THUMBNAIL_TEMPLATE and PREVIEW_FULL_TEMPLATE are useless

Use STATIC_URL for statics, not MEDIA_URL

Do not use STATIC_URL for urls serverd by django

Fix build_assets.sh with new static path

Wrong id number in string format

addons.button.js path is not more absolute (it's not a static)

Add collectstatic to fabfile and update.py

Do not override STATIC_URL in tests

working on dev settings

We don't use FILES_URL (downloads path comes from downloads.latest url)

MEDIA_ROOT is more like UPLOADS_PATH

Don't touch this part of prod settings for now

Let's use /storage/ for medias, as media is the old path of statics

The plan is to map MEDIA_URL to MEDIA_ROOT, which is UPLOADS_PATH

Remove settings that match default computed paths

Rebasing, god bless my git

gitignore storage/*

Use normal media url for themes

Wrong use of cache_buster