add STP parameters template
works with external_ids as with dictionary
start LNX provider for bridges
base classes for LNX and OVS providers
Make OSX provider suitable for Darvin-family OSes

+ move external_ids to the resource type
+ minimize notice count, correspond to vendor_specific and external_ids
+ describe verdor_specific for default providers leads to fail
+ describe external_ids for non-ovs based providers leads to fail
describe verdor_specific for default providers leads to fail

+ describe external_ids for non-ovs based providers leads to fail
remove confine
add comment to external_ids parameter