Remove git and add cyrus-sasl to dev environment

[ngoldbaum]

@robambalu hit issues with the self-signed SSL certificates on internal dev machines and conda's git, so let's remove it and just document that people need git installed.

Also adding cyrus-sasl, which it turns out is necessary if librdkafka is getting built on a machine with kerberos set up.

[timkpaine]

There are a few git options:

[http]
  sslCAPath = /etc/pki/ca-trust/source/anchors/
  sslVerify = false

You can point git at your trust store and/or disable SSL verification (obviously with the caveats that that has). I suspect that internally, /etc/gitconfig is doing one of these anyway (not that the system git is that much different from conda's git, just that conda probably has own $CONDA_PREFIX/etc/gitconfig).