portadmin tries to write to memory for each change

[John-Magne Bredal]

When doing changes, Portadmin tries to do a write mem to make the changes persist on Cisco devices. When doing bulk-changes this was done for each change, resulting in potentially many writes. As some devices use a lot if time to do a write mem, this lead to timeouts and related errors.

[John-Magne Bredal (john-m-bredal)]

Fix here: https://nav.uninett.no/hg/stable/rev/1a7e489a115e