Combined file.keyvalue_list and file.keyvalue
Combined file.keyvalue_list and file.keyvalue

integration.states.test_file.FileTest.test_keyvalue was already
testing the file.keyvalue function since it used file.keyvalue_list
already.

Now there is only one function; file.keyvalue which takes either
2 parameters (key, and value) or a dictionary key_values to handle
multiple key values in a single file all at once.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt