* Add 100% test coverage for the kubernetes.secret_present state
* Add 100% test coverage for the kubernetes.configmap_absent state
* Add 100% test coverage for the kubernetes.configmap_present state
* Make some fields optional to kubernetes.create_secret and add examples
* Make some fields optional to kubernetes.replace_secret and add examples
* Make some fields optional to kubernetes.create_configmap and add examples
* Make some fields optional to kubernetes.replace_configmap and add examples
* Add 'comment' when a kubernetes configmap or secret is going to be replaced
* Update 'source', 'template', and 'saltenv' kwargs to defaults from the rest of the codebase
* Allow passing empty 'data' to the kubernetes.configmap_present state to remove the existing contents

* Add 100% test coverage for the kubernetes.secret_absent state
* Add 100% coverage for kubernetes.node_label_present
* Also add 'comment' to kubernetes.node_add_label
* Make the faux test objects more believable in test_kubernetes.py

This bug found courtesy of writing unit tests to ensure it worked! When
a namespace is created via `kubernetes.namespace_present`, the 'result'
key of the return dict stays the default of `False`, which is confusing
after it is actually created.

TDD, finding your problems, just like mom!

* Add 100% test coverage for the kubernetes.node_label_absent state
* Add 100% test coverage for the kubernetes.namespace_present state
* Add 100% test coverage for the kubernetes.namespace_absent state