Adding skeleton swagger UI

Adding a skeleton Swagger UI:

![syt4qvs42d](https://cloud.githubusercontent.com/assets/10199099/5512715/5f35cfe8-8795-11e4-8c5f-42a5cb863247.png)

It picks up the swagger spec from /swaggerapi, which right not looks like:
![jca3tugm2o](https://cloud.githubusercontent.com/assets/10199099/5512724/9a6690de-8795-11e4-9f78-161d2f471de1.png)

The next step is to improve that spec.
I wanted to get feedback on this, while I figure out how to do that.

Changes made are as follows:
1. Copied https://github.com/swagger-api/swagger-ui/tree/master/dist/* to www/swagger-ui/* (as instructed in swagger-ui docs)
2. Modified www/swagger-ui/index.html to use ../../swaggerapi/ for the spec (again, as per swagger-ui docs)
3. Ran hack/build-ui.sh to update pkg/ui/datafile.go
4. Updated master.go to set the appropriate SwaggerPath and SwaggerFilePath in swaggerConfig.

This is step 2 of the steps mentioned here: https://github.com/GoogleCloudPlatform/kubernetes/issues/1052#issuecomment-62673812