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 )
There is also the case where neither `nconf.stores.user.file` nor `nconf.stores.global.file` exists. In that case, write to `nconf.stores.user.file` (since that is likely writable by the process).

Also, it would be good to actually display the path to the file that will be saved in the web admin interface, so that sysadmins know where things are being read from and where they will be saved.

A future enhancement (not for this issue) would be to give visual feedback of some sort to indicate which values are default values, and which ones have been modified, and the ability to rest them to their default values (but don't do that for this PR, that is something we'd place a separate bounty for).