Resolves: #2628 adds a destructor into SessionManager to call writeClose, writeClose now checks to see if the storage is immutable prior to attempting to save since the destructor may call writeClose a second time
Merge branch 'hotfix/session-savehandler-db-destruct' of git://github.com/mwillbanks/zf2 into hotfix/3429
Merge branch 'hotfix/3429'

Close #3429
Fixes #2628
Fixes #3075
Fixes #3108
Fixes #3182