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

@@ -1,6 +1,7 @@
 ### HEAD
 
-* Remove mapping of `.php` files to `text/html`
+* Remove the mapping of `.manifest` files to the `text/cache-manifest` media type.
+* Remove the mapping of `.php` files to the `text/html` media type
   [[daab35b](https://github.com/h5bp/server-configs-apache/commit/daab35bc91c299da23efdfa740f13a46ad10612a)].
 
 ### 2.12.0 (March 2, 2015)

dist/.htaccess

@@ -217,7 +217,7 @@ Options -MultiViews
     #       </Files>
 
     AddType application/x-web-app-manifest+json         webapp
-    AddType text/cache-manifest                         appcache manifest
+    AddType text/cache-manifest                         appcache
 
 
   # Media files

src/media_types/media_types.conf

@@ -61,7 +61,7 @@
     #       </Files>
 
     AddType application/x-web-app-manifest+json         webapp
-    AddType text/cache-manifest                         appcache manifest
+    AddType text/cache-manifest                         appcache
 
 
   # Media files

test/fixtures/.htaccess

@@ -197,7 +197,7 @@ Options -MultiViews
     #       </Files>
 
     AddType application/x-web-app-manifest+json         webapp
-    AddType text/cache-manifest                         appcache manifest
+    AddType text/cache-manifest                         appcache
 
 
   # Media files

test/tests.js

@@ -287,13 +287,6 @@ exports = module.exports = {
                     }
                 },
 
-                'test.manifest': {
-                    responseHeaders: {
-                        'cache-control': 'max-age=0, no-transform',
-                        'content-type': 'text/cache-manifest'
-                    }
-                },
-
                 'test.map': {
                     responseHeaders: {
                         'cache-control': 'max-age=0, no-transform',