Jwang add watchdog

[jingjingwang]

PS the watchdog is running on vega:8385.
To test, update the deployment.cfg file to contain watchdog information, launch the cluster so it can register itself, and click the restart button on myria-web (uwescience/myria-web#109) to restart.

[coveralls]

Coverage increased (+0.03%) when pulling 23a6ec1 on jwang_addWatchdog into 1ac65d4 on master.

[coveralls]

Coverage increased (+0.03%) when pulling f3fbf27 on jwang_addWatchdog into 1ac65d4 on master.

[coveralls]

Coverage increased (+29.49%) when pulling 7ac7ae8 on jwang_addWatchdog into 1ac65d4 on master.

[dhalperi]

A few meta-comments:

1. I'm not sure this tool belongs in Myria proper. Seems worthy of its own repository both to make it self-contained and also to make it testable.
2. I don't like the idea of the system registering itself with the watchdog. I think the administrator should be required to register the deployment with the watchdog, and the system should be entirely unchanged and unaware.

[dhalperi]

Here's my rationale for 2 -- if we change the system's behavior to fit the watchdog, then it increases the combinations of tests we have to support. Does the system come up correctly if the watchdog is down? Does it shut down correctly when the watchdog is down? Does it work if the watchdog enters an undefined state? etc.

[jingjingwang]

I've been thinking about 2 for a while and I think it's a good idea. Although the current implementation has no such issues, it's good for the future. (and simplifies my life too)
For 1, I'm happy to have a new repository. I thought about it but was feeling too much for such a script. Should I go ahead and open a new repository?

[jingjingwang]

Hi @dhalperi, seems I don't have the permission to create a new repository. Could you do it? Thanks!