camli client config alias

* `server`: The camlistored server to connect to, of the form:
  "[http[s]://]host[:port][/prefix]". Defaults to https. This option can be
  overriden with the "-server" command-line flag.

    Most client commands are meant to communicate with a blobserver. For such commands, instead of the client relying on discovery to choose the actual URL, the server URL can point directly to a specific blobserver handler, of the form:
"[http[s]://]host[:port][/prefix][/handler/]".

    For example, if one wanted to speed up syncing with `camtool sync`, one could write directly to the destination's blobserver, instead of the default, which is to write to both the destination blobserver and index. The above configuration sample can be extended by adding the following alias, where "`/bs/`" is the handler of the primary blobserver:

        "servers": {
          ...
          "backup-bs": {
            "server": "https://some.remote.com/bs/",
            "auth": "userpass:pony:magic",
            "trustedCerts": ["ffc7730f4b"]
          }
        }

    And the alias `backup-bs` can then be used as a destination by `camtool sync`.