fix(router): dump host/port info into json object

These keys are currently unused by anything, but will help users use
these keys with confd 0.6.

See https://github.com/kelseyhightower/confd/blob/master/docs/templates.md#create-the-template
fix(router): use string instead of JSON

This format can be consumed without structured data handling. For
example, bash has no builtin commands which handle JSON data structures.
docs(router): update router's published keys
Merge pull request #2131 from bacongobbler/router_num

fix(router): publish routers to /deis/router/hosts