Active display: allow hiding low priority notifications. [1/2]

ps2: COPY/PASTA

Change-Id: I4831d6864b509e62b449c25619c59f5d6760ec47
active display: minor fixes

make sure quiet hours setting is observed

Change-Id: Idddb6b251519ab122ae32d70d1de2ee6d942765e
Allow multiple emulated storages at the same time.

Only do multiuser mapping for primary emulated storage as per google docs.
Allow all non-primary emulated storage to have id other than 0 so that
it could be distinguished from the primary volume.

Change-Id: I7b70b9067fd6211055fb9074710f48107d7b0e8e