OCD is making me fix the inconsistency with how None is typed. First Letter Capitalized All Over Now.
cleaning up the default object that was created for the cache_security_groups and removing checks dealing with it.
clean up space
Changing default cache_security_groups from [default] to None.
I think in this commit 720aeffca2
There was bug introduced where the ElastiCacheManager init method has
a number of positional arguments like so.
```py
def __init__(self, module, name, engine, cache_engine_version, node_type,
num_nodes, cache_port, parameter_group, cache_subnet_group,
cache_security_groups, security_group_ids, zone, wait,
hard_modify, region, **aws_connect_kwargs):
```
But then later in the code the positional arguments are passed in
like this.
```py
elasticache_manager = ElastiCacheManager(module, name, engine,
cache_engine_version, node_type,
num_nodes, cache_port,
cache_subnet_group,
cache_security_groups,
security_group_ids, parameter_group, zone, wait,
hard_modify, region, **aws_connect_kwargs)
```
If you count, you can see that cache_subnet_group, is being passed in
where the manager expects to see parameter_group.
- removed import of sys module.
- HAS_BOTO constant to check if import was successful.
- trigger a failure when import fails.
- removed unnecessary imports.
