Don't start upr_event_t enum at 101

This was done originally because the tap and upr events might have
been passed in to the same variables. Starting at 101 would avoid
conflicts. We no longer use upr_event_t like this.

Change-Id: I80adaead6877ec7cd72a9b430a04b3797b25440f
Reviewed-on: http://review.couchbase.org/34462
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Junyi Xie <junyi.couchbase@gmail.com>