Fix time range selection during search

The previous version did not work in Chrome browser.

Closes #1102

[mod] simple theme: add the license to different files.

[fix] autocompleter py3 compatibility - fixes #1088

[fix] use english in google engine if no language was set - this prevents guessing the language by the IP of the instance

Dependencies upgrade

https://pypi.python.org/pypi/pyOpenSSL : fix memory leak
http://lxml.de/4.1/changes-4.1.1.html : speed improvement

[doc] add @vachi, @lcpz, @nikaiw, Thirnearez, @MrPetovan, @woorst, @Apply55gx, @pyrrh0n1c, @cclauss, @moon2l to authors

fix bug: TypeError: set(['bing', 'google']) is not JSON serializable,…

fix bug: TypeError: set(['bing', 'google']) is not JSON serializable, when curl 'http://127.0.0.1:8888/?q=xxxxxxxx&categories=general&format=json'

print() is a function in Python 3

Fixed the currency_convert engine.