docs: adapt built in acetate helper to fix sticky links

[jgravois]

ISSUES CLOSED: #284

🎩 tip to @paulcpederson for pointing out that its actually a helper built right into acetate that helps us set the is-active class automatically when a page loads.

it feels like a wretched hack to me to copy/paste the entire helper (and its dependencies) into this library, but i couldn't think of a more clever way to extend the logic in the comparisons.

${BASE_URL}${currentUrl}` === `finalUrl`

// instead of 
currentUrl === finalUrl

@paulcpederson also mentioned that we might should be using {{ relativePath }} in this website to make our lives easier, but i couldn't get that option to behave either.

{% link relativePath + "api/", "API Reference", class="side-nav-link"%}

// .api/ ?

{% link relativePath + "/api/", "API Reference", class="side-nav-link"%}

// /api/ ??

[coveralls]

Coverage remained the same at 100.0% when pulling eafcdd1 on docs/284 into be11aa1 on master.

[paulcpederson]

@jgravois you could also just not use the link helper rather than replicating it and changing it inside your project.

This seems to work pretty well:

<nav class="top-nav-list" role="navigation" aria-labelledby="topnav">
  <a href="{{relativePath}}/guides/" class="{% if url == '/guides/'%}is-active{% endif %} top-nav-link">Guides</a>
  <a href="{{relativePath}}/api/" class="{% if url == '/api/'%}is-active{% endif %} top-nav-link">API Reference</a>
</nav>

[patrickarlt]

@jgravois this should already be built into Acetate. http://acetate.io/documentation/built-in-helpers/ > Link Helper. Is something wrong with that version? The follwoing should just work in templates {% link '/guide/', 'Guide' %}

[jgravois]

thanks @paulcpederson. doing that for each of the individual 'link`s in the API reference sidebar probably is a better option than hacking on the built in helper.

@patrickarlt i wouldn't say there's anything wrong with what is built into acetate. it just doesn't account for the fact that we added a utility in #83 to prepend our baseurls with /arcgis-rest-js/ only when we are building for production.

{% link baseUrl + package.pageUrl, package.pkg.name %}

this was the best idea we could come up with to host the doc at https://esri.github.io/arcgis-rest-js/.

there's likely a way to configure the raw source to achieve both lofty goals simultaneously, but the exact path eludes me.

[jgravois]

there's likely a way to configure the raw source to achieve both lofty goals simultaneously

figured it out in #341