Ensure RT incremental update not applied early

Ensure RT incremental update not applied early

This change ensures that a full table has been provided by the
route generator (route manager) prior to RMR accepting any
incremental updates.

The change also captures the initial value of the RMR_SEED
environment variable such that it cannot be changed once it has
been used.

Issue-ID: RIC-329

Signed-off-by: E. Scott Daniels <daniels@att.com>
Change-Id: I168cb42905e41641590130de724965e8dbca67e6