!!!BUGFIX: Make session caches persistent by default
!!!BUGFIX: Make session caches persistent by default

Previously the sessions would be flushed whenever caches get flushed. This sometimes leads to unexpectedly logging out users, as happens for example in the neos setup in the last step.
This is only breaking in the sense, that you need to take care when deploying code that changes classes or data stored in the session. In those cases you need to flush the session caches manually via './flow flow:cache:flushOne Flow_Session_MetaData && ./flow flow:cache:flushOne Flow_Session_Storage`.

Resolves #1390
robertlemke/flow-development-collection,dlubitz/flow-development-collection,dlubitz/flow-development-collection,neos/flow-development-collection,kdambekalns/flow-development-collection,neos/flow-development-collection,daniellienert/flow-development-collection,bwaidelich/flow-development-collection,daniellienert/flow-development-collection,daniellienert/flow-development-collection,robertlemke/flow-development-collection,neos/flow-development-collection,kdambekalns/flow-development-collection,robertlemke/flow-development-collection,robertlemke/flow-development-collection,bwaidelich/flow-development-collection,albe/flow-development-collection,fcool/flow-development-collection,kdambekalns/flow-development-collection,dlubitz/flow-development-collection,kdambekalns/flow-development-collection,bwaidelich/flow-development-collection,fcool/flow-development-collection,fcool/flow-development-collection,albe/flow-development-collection,neos/flow-development-collection,fcool/flow-development-collection,albe/flow-development-collection