Docs: "View on Github" links are not correct.

[HenriqueLimas]

The links for the services $mdIcon, $mdIconProvider and $mdMedia are not correct on the documentation.

The correct links are:
$mdMedia - https://github.com/angular/material/blob/master/src/core/util/media.js
$mdIcon and $mdIconProvider - https://github.com/angular/material/blob/master/src/components/icon/iconService.js

[marcysutton]

The gulp process needs to pull out filenames as it assembles the docs. That way, they will always be in sync and we don't have to follow as specific of naming conventions.