debian: Pass 100 to UID_MIN and GID_MIN, not 1

debian: Pass 100 to UID_MIN and GID_MIN, not 1

According to the policy, UIDs and GIDs in the range 1-100 are reserved
to be globally allocated by the base-passwd package. The libuuid1
postinstall script passes in UID_MIN=1 and GID_MIN=1.  The useradd and
groupadd commands seems to skip UID's between 1 and 100 anyway, but
it's confusing, so we should pass in UID_MIN=100 and GID_MIN=100 for
clarity and in case useradd and groupadd ever changes their behaviour.

Addresses-Debian-Bug: #466929

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>