filter by multiple reviewers

[mmelot]

Issue1
gerrit patches --not-reviewed --branch=mybranch --reviewer=user1,user2
OR
gerrit patches --not-reviewed --branch=mybranch --reviewer=user1 --reviewer=user2

Issue2
Further more add a reviewer column to
gerrit patches --not-reviewed --branch=mybranch

Issu3
I didn't see good example of --age=value
how is this intended to use and what value does it acccepts