Add two features

Hi,

I added two features:

* `git_open_config_url` enables to open url from git config file.

By default, it opens the url returns by the command:

	git config remote.origin.url


* `git_execute` enables to execute several git commands in a row when they are separated by `;`

For instance, you can define your name and email in one click:

    {
        "caption": "Git: User",
        "command": "git_execute", "args": {"cmd": "git config user.name User;git config user.email User@users.noreply.github.com"}
    }


Hope it helps.