sync upstream v0.15.0 to get last changes and fixes

See merge request e/cloud/my-spot!17

Fix spacing between 'more', and language,
Bottom url in results is now a link

Before this, selecting next page in image gallery would put you in general search again,
also fixed mixed video results on first page, that needs to be handled the same as first
page images (currently missing).

Release v0.15.0

[add] mojeek engine

[fix] google videos engine

Remove Ixquick engine

restore startpage search results

Fix bing image thumbnail path

- Forget one "\" in the process!

Instead of a single line with 500000 characters use nicely formatted JSON.
Sort the lists in engine_languages.py so when updating it is possible to
more easily see the differences (search engines do change the order their
languages are listed in)

[add] seznam engine

Update Dockerfile

- Fix for docker image build error "Could not find a version that satisfies the requirement cffi!=1.11.3,>=1.7 (from versions: )"