BREAKING: Remove transform option (#250)

Users can use the load option for this.

Author: RyanZim

README.md

@@ -126,23 +126,6 @@ Default: `[]`
 
 A string or an array of paths in where to look for files.
 
-#### `transform`
-
-Type: `Function`  
-Default: `null`
-
-A function to transform the content of imported files. Take one argument (file
-  content) and should return the modified content or a resolved promise with it.
-`undefined` result will be skipped.
-
-```js
-transform: function(css) {
-  return postcss([somePlugin]).process(css).then(function(result) {
-    return result.css;
-  });
-}
-```
-
 #### `plugins`
 
 Type: `Array`  

index.js

@@ -308,15 +308,6 @@ function loadImportContent(
   }
 
   return Promise.resolve(options.load(filename, options))
-  .then(function(content) {
-    if (typeof options.transform !== "function") {
-      return content
-    }
-    return Promise.resolve(options.transform(content, filename, options))
-    .then(function(transformed) {
-      return typeof transformed === "string" ? transformed : content
-    })
-  })
   .then(function(content) {
     if (content.trim() === "") {
       result.warn(filename + " is empty", { node: atRule })