New: Added Admin page (fixes #30)

Fixes #30

Following are the changes made:

* Supports save and reload of config.
* Picks up the config with a higher priority as mentioned in the README.
* Runs with ```grunt admin```
* Uses react and coffeescript

Any suggestions on how to go about on the below points?

* Support of https ( Need certificates. Related to #58? )
* Restart of other servers on save. (Should ```example.coffee``` be made a module?)
* Graph ( depends on #10 )
Although, I am not sure... Please look closely at [these lines from `config.coffee`](https://github.com/vegetableman/dnschain/blob/admin/src/lib/config.coffee#L84-L90).

Notice that the file that could be used is `nconf.stores.global.file`, not `nconf.stores.user.file`. However, I think it is possible (would need to test to be sure) that this code would run anyway, even if the admin expects the changes to be saved in `/etc/dnschain/dnschain.conf`, because if the `HOME` environment variable exists, `nconf.stores.user.file` may be defined.

So, you need to be aware of this in all places where you're currently using `nconf.stores.user.file`. Instead of using that, use whatever file actually exists. It could be `nconf.stores.user.file`, or it could be `nconf.stores.global.file`. Whichever file exists is the one that should be used.