Add aria-required, autocomplete attributes to forms

- We don't want autocomplete on the webmention form, since users should
  not be entering a link multiple times.
- Not all browsers support the "required" HTML5 attribute, so add the
  "aria-required" HTML attribute too.

layouts/partials/search.html

@@ -10,7 +10,7 @@
 		<meta itemprop="urlTemplate" content="{{ $action }}?q={q}" />
 	</label>
 	<div><!--We need the extra divs to serve as pseudo-table-cells.-->
-		<input itemprop="query-input" id="search" type="search" required="" name="q" />
+		<input itemprop="query-input" id="search" type="search" required="" aria-required="true" autocomplete="on" name="q" />
 		<div><input type="submit" value="search" /></div>
 	</div>
 </form>

layouts/partials/webmention-form.html

@@ -8,7 +8,7 @@
 		<input type="hidden" name="target" value="{{ .Site.Params.canonicalBaseURL }}{{ $canonicalRelPermalink }}" />
 		<label for="menchie">URL of page linking here</label>
 		<div><!--We need the extra divs to serve as pseudo-table-cells.-->
-			<input id="menchie" type="url" required="" name="source" />
+			<input id="menchie" type="url" autocomplete="off" required="" aria-required="true" name="source" /><!--disable autocomplete bc it's a unique URL.-->
 			<div><input type="submit" value="submit" /></div>
 		</div>
 	</form>