adds the missing Code of Conduct file

This adds the NGINX Code of Conduct file to the repo. This is one of the community guides required and is recognized by GitHub insights.

Clarify that this project is not designed for production work

Escape Username in LDAP search filters 

Fix for Python3

Python3compatibility

It is now possible to run testsuite in docker, using supplied file.
See instructions in t/README.

Tests are adjusted to run on alpine linux which includes modular builds
of openldap server software.

Add chcecks for version for importing and decoding bytestring.
Inspired by PR #66

On used docker baseimage python is already linked to python2 or python3,
depending on image version

With this anyone can effectively use Python 2 or 3 using --build-arg
The default version is 2.

Formating fixed and optimized

Fix logrotate and update rpm spec file

* Create log directory in spec file
* Fix logrotate file

The directory is distributed on two servers, and search now may return
continuation object for specific users.

This fixes https://github.com/nginxinc/nginx-ldap-auth/issues/55.

It was possible to perform successful bind with unknown user with recent
versions of python-ldap, in case when LDAP server returned continuation
object and allowed anonymous bind.

The testsuite depends on nginx test suite, and requires an OpenLDAP server
installed.

Add Comment for HTTP basic authentication.

The options is boolean, header name is  'X-Ldap-DisableReferrals' and
the command-line switch is '--disable-referrals', default value is
false.

create missing etc/logrotate.d directory in buildroot

This is a rebased version and slightly modified version of patch submitted by
Matthieu Cerda <matthieu.cerda@gmail.com> via pull-request #29
(https://github.com/nginxinc/nginx-ldap-auth/pull/29)

The correct name starts with the lowercase 's'.

https://msdn.microsoft.com/en-us/library/ms679635