Allow "api" and so-called sections in domains, subdomains

Without this fix, if any string that appears in `<%= sections %>` is also in the domain or subdomains of the web server hosting ngdocs, `baseUrl` will not be correct, and all the JS and CSS resources will fail to load.

For example, we're hosting ngdocs at https://cdn-angular-api.example.com/ngdocs. Because the subdomain has "api" in it, `baseUrl` is set to `http://cdn-angular-` and all the `<link>` and `<script>` assets become 404s. 

This fixes that by not using `location.href` against the `rUrl` regex. Instead, apply `rUrl` to only the portion of the `location.href` that doesn't include `location.origin`.