don't download _base image on launch

Change-Id: I6bed4511f0bd035bfa87f562e728a3be8049ebd9
Update setup.py to contain the list of dependencies.

Change-Id: I4b034455f4f38028a4c47d9a70793265dc207c10
Updating hypervisor_hostname on launched instances.

In Grizzly instances now have a 'node' field that maps to the
'hypervisor_hostname' attribute instances returned by the API.
On cobalt-compute startup we query the hypervisor through the
vms_conn to determine this value and apply it to instances whenever
we set their host field.

Change-Id: I0be721b351c4d6429c77ed3134e642cd902509fd
Create symlink from LVM path to qcow2 file when launching

Regardless if nova is configured to use LVM cobalt will always use
qcow2 files when launching an instance. However, we still need
something at the LVM path location because nova will reconfigure
things on reboots. To handle this cobalt will create a symlink at
the LVM path location that targets the qcow2 root disk.

Change-Id: I41411d27d4dea2de5d79be4a66b8ca9286ce5335
fix launch: path=None unless using image service

A bug was introduced in 7c1f27b67d53c97ef0eb417564ba16df70db1979
wherein the base_ image directory was always given as the path
argument to to vms.management.Management.launch, thereby overriding
VMS_DISK_URL. Since the path argument to launch tells it where to look
for artifacts (descriptor files, base disks, etc.), we only want to
set it to nova's base_ directory when we're using glance to store
bless artifacts.

Change-Id: I59261b4c99f03fb2c129077d9e5b7538bd547b42
Some test stuff. Faster.
Conductor stuff.
WIP 3
Passes the tests.