site: support permalinks. fixes #184

This does a few things to support permalinks. First, methods are isolated to their own page, e.g. docs/datastore/dataset/runQuery. They can be accessed via the `/` url (so a reader can copy and paste the url in the address bar to share), or if they come from one of our jsdoc reference links: https://github.com/GoogleCloudPlatform/gcloud-node/blob/master/lib/datastore/query.js#L33, a url like: docs/datastore/dataset#runQuery will do a seamless replacement of the `#` to a `/`, and take the user to the right spot.

If a specified method doesn't exist, they are directed to the class documentation.

~~Also, I just found a bug. Will report back when it's good to go :+1:~~

Update: good to go. Here're some links:

http://stephenplusplus.github.io/gcloud-node/#/docs
http://stephenplusplus.github.io/gcloud-node/#/docs/datastore/dataset
http://stephenplusplus.github.io/gcloud-node/#/docs/datastore/dataset/runQuery
http://stephenplusplus.github.io/gcloud-node/#/docs/datastore/dataset#runQuery
I think this should be `/gcloud-node/docs/`... because some links are working for me like 'the Dataset documentation' link on [this page](http://stephenplusplus.github.io/gcloud-node/#/docs/datastore)