Return all installed services

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_all

def get_all():
    '''
    Return all installed services

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_all
    '''
    ret = set()
    cmd = '/usr/bin/svcs -aH -o FMRI,STATE -s FMRI'
    lines = __salt__['cmd.run'](cmd).splitlines()
    for line in lines:
        comps = line.split()
        if not comps:
            continue
        ret.add(comps[0])
    return sorted(ret)