Launchpad ingestion to archive endpoint

Wire up launchpad ingestion to charmstore filling out new api/models.
@jrwren sorry about that, I was thinking about different logs for different scenarios, like charmload-errors, or charmload-failed, etc. and somehow made this comment about adding _v4 as postfix. 
@rogpeppe lpcharmload ... it will load bundles as well. lploader or ingestLP maybe?