update and fix search engines

I have found out that many search-engines need rework.

Currently, I have checked and rewrite the engines from bing, google, yahoo and dailymotion

* adding comments (including header with general informations)
* rewrite http to https url if possible
* fix language support
* delete unused code
* fix bugs like no results, wrong template
* decrease results/page for dailymotion
* add bing_images

There are much more engines availabe in searx, so I hope anyone can help me to bring that pice of code up-to-date.