Remove the .manifest → text/cache-manifest mapping

Four years ago the recommended file extension for AppCache manifest
files was changed¹ from `.manifest` to `.appcache`. So, even adding
into consideration the transitional period, it no longer makes sense
to keep the configurations that ensure that `.manifest` files are
served with the AppCache required `text/cache-manifest` media type.

Also, recently, `.manifest` became one of the recommended file
extensions for web application manifest² files.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

¹ https://html5.org/r/5812
² http://w3c.github.io/manifest/

CHANGELOG.md

@@ -1,5 +1,6 @@
 ### HEAD
 
+* Remove the mapping of `.manifest` files to the `text/cache-manifest` media type.
 * Change media types for `.atom` and `.rss` files
   [[#90](https://github.com/h5bp/server-configs-apache/issues/90)].
 * Minimum nginx version upped from 1.2.1 to current stable, 1.6.0.

mime.types

@@ -26,7 +26,7 @@ types {
 
 # Manifest files
   application/x-web-app-manifest+json   webapp;
-  text/cache-manifest                   manifest appcache;
+  text/cache-manifest                   appcache;
 
 # Microsoft Office
   application/msword                                                         doc;