SmartOS support

Hi,

Added SmartOS support for fabric.

Feel free to spin up a box on Joyent and test using the following snippet:

env.hosts = ['joyent_box']

    def provision():
        pkg.update_index(force=True)
        pkg.upgrade(full=True)
        pkg.install('top')
        if pkg.is_installed('top'):
                print(green('top is installed'))
        if not pkg.is_installed('redis'):
                print(red('redis is not installed'))
        pkg.install('unzip', update=True, options=['-V'])
        pkg.uninstall(['unzip', 'top'], orphan=True)
        if pkg.smartos_build().startswith('joyent'):
                print('SmartOS Joyent')
        print(cyan(pkg.smartos_image()))