Return True if jail exists False if not

    CLI Example:

    .. code-block:: bash

        salt '*' poudriere.is_jail <jail name>

def is_jail(name):
    '''
    Return True if jail exists False if not

    CLI Example:

    .. code-block:: bash

        salt '*' poudriere.is_jail <jail name>
    '''
    jails = list_jails()
    for jail in jails:
        if jail.split()[0] == name:
            return True
    return False