removed db:sessions:clear from upgrade tasks
removed db:sessions:clear from upgrade tasks

can result in logging everybody out, and is not really needed any more

HITS-SDBV/seek,HITS-SDBV/seek,stuzart/seek,SynthSys/seek,SynthSys/seek,stuzart/seek,SynthSys/seek,HITS-SDBV/seek,HITS-SDBV/seek,SynthSys/seek,stuzart/seek