planner signature change

[manishtomar]

There have been occasions where a new config was required by convergence planner. This was added as new argument to planner requiring changes everywhere it is called including tests. Now, it looks like planner needs CLB health info and node OFFLINE timeout as arguments #1870. To avoid changing signature again I think planner should be:

def planner(desired_group_state, resources, config, now):
     pass

where resources is simple object containing servers, lb_nodes, lbs or any other future resources and config is another object containing configuration like build_timeout, steps_limit, node_timeout or any other future values.

@attr.s
class Resources(object):
    servers = attr.ib()
    lb_nodes = attr.ib()
    lbs = attr.ib()

@attr.s
class Config(object):
    build_timeout = attr.ib()
    steps_limit = attr.ib()
    node_timeout = attr.ib()