Source Code links broken in doc site

[quartzmo]

Steps to reproduce

1. Navigate to a docs page for a release using the new tag notation (<package>-<version>). For example:
   https://googlecloudplatform.github.io/google-cloud-node/#/docs/datastore/0.3.0/datastore

2. Click any "Source Code" link in the page.
   

   For example:
   https://github.com/GoogleCloudPlatform/google-cloud-node/blob/0.3.0/packages/datastore/src/index.js#L305

   Result is 404. Correct URL should be:

   https://github.com/GoogleCloudPlatform/google-cloud-node/blob/datastore-0.3.0/packages/datastore/src/index.js#L305

This issue is the same as googleapis/google-cloud-ruby#908, reported by @omaray. I am guessing that the fix will involve updating the GoogleCloudPlatform/gcloud-common site.

[callmehiphop]

Ahh! Good find.. I think we're going to need a way to generate the correct tag name. Does everyone follow the {package}-{version} format?

Otherwise maybe we want to add the tag name to the toc.json file? Thoughts? @quartzmo @dwsupplee, @jdpedrie

[quartzmo]

We use a slash separator: {package}/{version} (I think the precedent we follow is git flow. Anyway, it is allowed.) Also, our package names are longer: google-cloud-datastore.

[callmehiphop]

Ok, well I think it might be easier/safer to just add the tag name to the toc.json? Otherwise we could just add some conditional logic in the app to try and guess it based on the language.

[quartzmo]

Tag name in toc.json sounds ok to me.

[jdpedrie]

We're not going to be able to split google-cloud-php into multiple packages for the foreseeable future, so allowing it to be configurable so we can opt out entirely makes the most sense to me.

[dwsupplee]

Configurable sounds best to me as well