pushover support

You need to add something like this to your plugin config:

        "pushover_plugin": {
            "api_key": "MY_API_KEY",
            "ignored_players": [# On branch pushover
                "Player1",# Changes to be committed:
            ],# (use "git reset HEAD <file>..." to unstage)
            "user_key": "MY_USER_KEY"#
        }