readFile/writeFile to read/write in file library.

as suggested by Bluebie.

lib/file.js

@@ -12,9 +12,9 @@ function debugObject (obj) {
   }
 }
 
-exports.readFile = node.fs.cat;
+exports.read = node.fs.cat;
 
-exports.writeFile = function (filename, data, encoding) {
+exports.write = function (filename, data, encoding) {
   var promise = new node.Promise();
 
   encoding = encoding || "utf8"; // default to utf8