Merge branch 'master' into fix-db
db: separate hub init and building of cached cfgs

... now that framework initialization pulls in so many hubs, reference
caching must be separated from hub initialization, else either user
config will refuse to overwrite the default empty value, or the cached
empty object remains stale. This is accompanied by an invocation to
build reference AFTER loading of config, in the shortcuts package.
db: fix wrong name of isinstance()...
session: add a Redis backend
Merge branch 'fix-db'
Merge branch 'redis-session'
pep8