Add /v1/agent/self and return local agent config

[tiwilliam]

This is a proposal for introducing a new API endpoint called /v1/agent/self. It returns the local agent's configuration as requested in #120.

This is an easier way to get the local state without trying to guess node using /v1/agent/members.

[armon]

This is a good start, but I think we want to include some additional information about the node's configuration. For example, people have asked about the configured DNS suffix (".consul"), and other configuration values. Maybe we make the response a larger JSON object of which the existing output is nested under "Member"?

[tiwilliam]

I see, thought this would be useful enough for most use cases. But might be nice to have the config as well. Would this be good:

{
    "Member": {
        "Name": "foobar",
        ...
    },
    "Config": {
        "Bootstrap": true,
        ...
    }
}

[armon]

Yeah, I think that should cover most of our basis for now!

[armon]

Thanks!