Merge tag '1flow-0.25.17.8' into develop

0.25.17.8 1flow-0.25.17.8
Merge branch 'release/0.25.17.8'
Move the `requests` absolutization in `Feed.prepare_url()`, this avoids some clashes.
When a feed url is added without the protocol part, assume it’s only the path part and try to guess the proto/host/port from the referrer if we have one. Spotted on http://filamentgroup.com/lab/update_jquery_ui_slider_from_a_select_element_now_with_aria_support/ with the bookmarklet.
version bump for 0.25.17.9.
Merge tag '1flow-0.25.17.9' into develop

0.25.17.9 1flow-0.25.17.9
Merge branch 'release/0.25.17.9'
Display a correct error message, even if the feed URL is really bad. Forward exceptions to sentry.
version bump for 0.25.17.10.
Merge tag '1flow-0.25.17.10' into develop

0.25.17.10 1flow-0.25.17.10
Merge branch 'release/0.25.17.10'
version bump for 0.25.17.11.
Merge tag '1flow-0.25.17.11' into develop

0.25.17.11 1flow-0.25.17.11
Merge branch 'release/0.25.17.11'
Remove `@cached` decorator on special feeds/subscription, this gives me the import feed of another user. The speedup is thus unusable, I have to find another way. + flake8 fixes.
version bump for 0.25.17.12.
Merge tag '1flow-0.25.17.12' into develop

0.25.17.12 1flow-0.25.17.12
Merge branch 'release/0.25.17.12'
Get the master feed if any. PEP8 love.
Forward the `Read` to the meta async template. Useless now, but needed for upcoming patches (restricted reads and al.).