Get away from master/slave vocabulary

[bopopescu]

For diversity reasons, it would be nice to try to avoid 'master' and 'slave' terminology in this repository which can be associated to slavery. The master-slave terminology could be problematic for people in several countries which has the history of slavery like Romania, USA and many others. Thank you for considering the proposal. Let me know if any changes in the PR are needed, I would be happy to implement them.

[kayousterhout]

Thanks for doing this; this is a great change to make. There's a bit more work necessary to make this work:

(1) The scripts like start_mesos_slave are present on the EC2 instance, so the path to the script can't be renamed without also renaming the underlying script.

(2) Similarly, the git branches that refer to "master" can't be renamed to "main" unless those branches already exist on Github.

(3) The slaves should be renamed to "worker" to match the Spark terminology.

(4) The boto files are an external dependency so should be updated in Boto rather than here (and then this repo could be updated to use the latest version of Boto).

This repo was last updated 7 years ago and is no longer maintained so I'm not sure this effort is worthwhile; I'm going to mark the repo as deprecated and add a note about the bad terminology used.