Support Python 3

[gmmeyer]

What does this PR do?

Support Python 3 on Mesos Slave

Motivation

🐍 3️⃣ 🚂

Review checklist

• PR has a meaningful title or PR has the no-changelog label attached
• Feature or bugfix has tests
• Git history is clean
• If PR impacts documentation, docs team has been notified or an issue has been opened on the documentation repo
• If PR adds a configuration option, it has been added to the configuration file.

Additional Notes

Anything else we should know when reviewing?

[codecov-io]

Codecov Report

Merging #2874 into master will decrease coverage by 20.31%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master    #2874       +/-   ##
===========================================
- Coverage   84.89%   64.58%   -20.32%     
===========================================
  Files         658        4      -654     
  Lines       37040      144    -36896     
  Branches     4396       32     -4364     
===========================================
- Hits        31445       93    -31352     
+ Misses       4314       38     -4276     
+ Partials     1281       13     -1268

[gzussa]

🤖 🤖 Sweet! Thanks