[fix] Read utf-8 files (settings, languages, currency) with Python3.5

Related to discussion in #1124
The io.open import is necessary for python2

Python3.5 is still the default Python3 version in
Debian Stretch (stable) and Ubuntu 16.04 LTS
https://packages.debian.org/source/stretch/python3-defaults
https://packages.ubuntu.com/source/xenial/python/python3-defaults

Make Python 3 able to read settings files with Unicode characters

Fix yacy engine

Closes #1064

SearX currently doesn't start up when run with Python 3 as it tries to parse the
settings.yml file with ASCII codecs.
There are similar problems with engines_languages.json and currencies.json
Python 3 requires that files with Unicode characters be read with a 'b' flag.
This also works with Python 2 and hence can be integrated into the main source
code.

Tested with the latest Python 3.6.4rc1 on Debian unstable.

Signed-off-by: Joseph Nuthalapati <njoseph@thoughtworks.com>

Logicodev-dark fixes

Fix google searches

Update readme

Stopped a sentence before it got out of hand.

Add links to footers of oscar and simple

Links:
 * Source code
 * Issue tracker
 * List of public instances

Closes #1071

[mod] simplify manage.sh

- npm install less@2.7 less-plugin-clean-css grunt-cli is moved inside manage.sh
- if it is possible to source manage.sh to update the PATH (to start grunt)
- tidy the help documentation
- update the geckodriver version to 0.19.1

Remove 'all' option from search languages

simple theme : magnet.svg is replaced by a home made version

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

Dependencies upgrade