Fixes #271

The opensearch method is now the method set in the preferences.

As before, POST by default and GET for Chrome/Chromium which doesn't
handle POST

[fix] btdigg: disable ssl check

[fix] #253

Moar engines

I didn't remove the engines files because it always could be helpful if they come back.

[fix] update yahoo engine according to the web site changes

This tab only purpose is to allow to see what searx is storing on the user's computer.

At a later time, we could implement a way to delete those cookies.

small update of russian translation

Remove whitespace and allow autocompleter to work in sub folders

Translations update

[fix] close #197 for all engines

Some RTL fixes