Fix filename extension leaking to json filename

Makes writeinfojson behaving exactly as writethumbnail in case where filename contains mediafile extension.

Case:

video.mp4 converted to music.mp3 would yield music.mp4.info.json instead music.mp3.info.json or music.info.json
Update test_write_info_json.py
Add support for anitube.se (#1417)
Add support for tou.tv (Fixes #1792)
Add an option to dump json information
import json for --dump-json
Merge remote-tracking branch 'dz0ny/patch-1'
[teamcoco] Correct error
Clean up unused imports and other minor mistakes
Merge remote-tracking branch 'diffycat/master'
Adapt test to changed .info.json name
[anitube] Minor fixes (#1776)
Credit @diffycat for anitube
[escapist] Add support for HD format (Closes #1755)