Renaming milpa to kip

[justnoise]

We have a lot of names in the codebase from when kip was called Milpa the software was a pretty cool stand-alone management controller. That time has passed and those references to Milpa need to be changed. I'm trying to keep track of those things here.

Easy to change

• security groups
• instances (node->cell, milpa -> kip)
• server.yml -> kip.yml or virtual-kubelet-provider.yml
• log messages

Harder to change but not as noticable to users

• paths in itzo filesystem (and references in cloud-init)
• paths in etcd

[justnoise]

I'm OK with how far we got on this issue before our release. We can update milpa log lines in time, the paths in etcd will stay for a while.