There is no point in specifying a default 'mem1' memory storage, which is used
for reading/listing/deleting, as those are operations that need a specific
'mem1' set each time.
Also, there is no point in specifying separate default 'mem2' and 'mem3' memory
storages, specially because now we allow Sms.Store() to specify a storage.
So, we will now only have a 'default' memory storage, which is applicable for
both 'mem2' and 'mem3' (storing, sending from storage and deleting).
bddcc2fb07