Support Python 3.5

[mprahl]

PostMaster currently supports 2.7 but an effort should take place to support both 2.7 and 3.5

[mprahl]

As of now, mockldap, which is used for our LDAP unit tests, uses python-ldap on 2.7, but uses pyldap on 3.5. Since python-ldap doesn't support Python 3.5, we are in a situation where we are stuck supporting only one version of Python.

[thatarchguy]

With the new LTS Ubuntu 16 supporting 3.5 out of box, I'm more comfortable with dropping 2.7 support in favor of 3.5.

I also dislike that one of our testing libraries is what is holding us back from supporting both 2.7 and 3.5. Maybe we can find a different library or fork?

Thoughts?

[mprahl]

@thatarchguy, a fork might be a good idea.

We could also just go ahead and convert entirely to 3.5 and leave behind 2.7.

[philof]

ldap3 supports python 2 & 3. It adds a few benefits:

• It's pure python, so it doesn't rely on ldap client libs (libldap2-dev)
• It can ease a transition between 2-3.
• It has built-in mocking, removing the need for mockldap.

[thatarchguy]

It has built-in mocking, removing the need for mockldap.

That solves it right there. Mock-ldap is holding us back.

[mprahl]

#176 addresses some of the issues. The next step would be to migrate to ldap3.

[mprahl]

Once #179 and #180 are merged, we should have Python 3.5 support. The next step is to have Travis test on Python 2.7 and 3.5, and to have Vagrant use Python 3.5 by default.

[miff2000]

This issue has the hacktoberfest label on it. Would you mind removing it @thatarchguy?

Python 2 was sunset 1st Jan 2020 and Python 3.5 became EOL 13th Sept 2020, by the way...