Tests/fix failing

Fixes failing tests when ran from inside vagrant. Hopefully this makes the tests happy on Travis after opening the pull request.

## Fixes

* `TestServer_globalRPCErrors` in `consul/server_test.go`

    Appears to need two servers since it checks for `remoteConsuls` to do a RPC call. If there aren't any it will return nil which previously made the test fail.

* Tests in `command/agent/agent_test.go`

    Were failing when trying to start up agents after a  shutdown. Turning the `Server` flag to `false` fixes these.
    Does this make sense or is they incorrectly passing with that change?
    Do the other tests in the agent test file need to have the `Server` flag set to true?