Re-order postBuild hook

Currently the postbuild is not very useful as it is called after everything is already in dist. The `results.directory` folder points to a directory that is going to get cleaned up soon after. This allows you to write to the final tree right before it is copied to dist.

lib/models/builder.js

@@ -116,8 +116,8 @@ module.exports = Task.extend({
        .then(function() {
          return self.builder.build.apply(self.builder, args);
        })
-      .then(this.processBuildResult.bind(this))
       .then(this.processAddonBuildSteps.bind(this, 'postBuild'))
+      .then(this.processBuildResult.bind(this))
       .catch(function(error) {
 
         this.processAddonBuildSteps('buildError', error);

tests/unit/models/builder-test.js

@@ -187,6 +187,22 @@ describe('models/builder.js', function() {
       });
     });
 
+    it('should call postBuild before processBuildResult', function() {
+      var called = [];
+
+      addon.postBuild = function() {
+        called.push('postBuild');
+      };
+
+      builder.processBuildResult = function() {
+        called.push('processBuildResult');
+      };
+
+      return builder.build().then(function() {
+        expect(called).to.deep.equal(['postBuild', 'processBuildResult']);
+      });
+    });
+
     it('buildError receives the error object from the errored step', function() {
       var thrownBuildError = new Error('buildError');
       var receivedBuildError;