first pass at layer refactoring, with passing test suite
remove south for now
use layer to define run_list and initial attributes
move key functions, remove image from formation required args
move default cloud init into FlavorManager
move initial_attributes into layer
number nodes by layer
add run_list and initial_attributes conditionally
replace formation scaling with layer & container scaling
move cloud infrastructure fields from formation to layer
include formation name in layer infrastructure
destroy layer infrastructure on DELETE
switch to get_object_or_404 on layer views
only apply jobs if defined
new batching logic for formation/layer destroy
add layers:destroy, change layers:create args
change register url to match other auth urls
remove commented line
fix sg_name bug
add node deletion