Return VNC port in show_headnode

There's a little bit of (documented) trickiness, in haas/model.py

This needs to be deployment-tested.
Return port 'None' instead of -1
Document return value for no_dry_run decorator
Use an XML parser to parse XML
Add an api call to power cycle a node.

This involved a handful of changes:

1. Add three columns to the Node class, with ipmi-related info.
2. Add corresponding parameters to Node.__init__ and node_register.
3. Add the api call itself, node_power_cycle.
4. Add the cli wrapper.
5. Update some of the tests due to (2).
Headnode-create deployment test and supporting decorators.
Added node allocation to deployment_test decorator.
Merge branch 'remove-port' of https://github.com/gsilvis/haas into deployment-tests-vlan-fix
Added isolated network test
Finished network isolation test for deployment tests.
Fixed a bug in the hnic_cleaup decorator that prevented it from deleting the appropriate VLANs.
Included disclaimer in deployment tests docstring, removed commented out PDB statements, and fixed a typo in a comment.
Updated docstring for deployment.py to include disclaimer.
Fixed typos in comments and futher explained the deployment_test decorator.
Merge branch 'deployment-tests' of https://github.com/ryabouza/haas into devel
In no_dry_run, return return-value of called function
Make do without check_output in python-2.6
Merge pull request #206 from zenhack/powercycle-proxy

Add an api call to power cycle a node.
Add script to prepopulate vlans
Don't re-create bridges in model.py