Added build watch for e2e tests

As a follow up from #323 I've added build watch, I'm looking for you comments @bparees @ironcladlou 
Looking at how cleanly upstream does polling w/ the template functionality makes me wonder if I was wrong about using watches:

https://github.com/GoogleCloudPlatform/kubernetes/blob/master/hack/e2e-suite/basic.sh#L40

What do you think? I think that the template-to-get-a-list which can be fed right to a bash for loop is way clean and simple...