Previously the bitseq alloc was allocating the first available bit from the
begining of the sequence. With this commit the bitseq alloc will proceed
from the current allocation. This change will affect the way ipam and vni
allocation is done currently. The ip allocation will be done sequentially
from the previous allocation as opposed to the first available IP.

Signed-off-by: Abhinandan Prativadi <abhi@docker.com>

Since bit allocation is no longer first available from
the start some verfications are removed/modified to
the change allocation model

Signed-off-by: Abhinandan Prativadi <abhi@docker.com>

Signed-off-by: Abhinandan Prativadi <abhi@docker.com>