Remove racially insensitive language

[nmerket]

The big one is the fact that we're mirroring the AWS EMR API by using the terms "master" and "slave" in our input file. I'm open to suggestions on what the updated terms should be. Maybe we should look at other projects that have a similar paradigm to see what terminology they use so we can be consistent.

Next, we should change the name of the master branch to something else. Github as a whole is moving this direction. This should be pretty easy, but could be disruptive to developers so will need to be coordinated. We have several repos, so maybe this change should be done in conjunction with others.

[rHorsey]

@nmerket I'm going to roll this into the new public ComStock repo as well. From what I can tell on twitter main has become the new recommended default (although I do love production not least of all because I can then ask why people aren't using production in production...) Are you seeing the trend towards main as well? Do you have significant thoughts one way or the other on this? I'm thinking standardized branches of main release/* hotfix/* develop feature/* and bug/* or main release-* hotfix-* develop feature-* and bug-*would set us up for success...

[nmerket]

I changed the main branch name to develop (easy). Still need to change the yaml keys.