Refactor and clean up code

ml-agents/mlagents/trainers/trainer_controller.py

                     container.
                 """
                 # Navigate in docker path and find env_path and copy it.
-                for f in glob.glob('/{docker_target_name}/*'.format(
-                        docker_target_name=docker_target_name)):
-                    if env_path in f:
-                        try:
-                            b = os.path.basename(f)
-                            if os.path.isdir(f):
-                                shutil.copytree(f,
-                                                '/ml-agents/{b}'.format(b=b))
-                            else:
-                                src_f = '/{docker_target_name}/{b}'.format(
-                                    docker_target_name=docker_target_name, b=b)
-                                dst_f = '/ml-agents/{b}'.format(b=b)
-                                shutil.copyfile(src_f, dst_f)
-                                os.chmod(dst_f, 0o775)  # Make executable
-                        except Exception as e:
-                            self.logger.info(e)
-                env_path = '/ml-agents/{env_name}'.format(env_name=env_path)
+                env_path = self._prepare_for_docker_run(docker_target_name,
+                                                        env_path)
             if curriculum_folder is not None:
                 self.curriculum_folder = \
                     '/{docker_target_name}/{curriculum_folder}'.format(
                                               'curriculum file has the same '
                                               'name as the Brain '
                                               'whose curriculum it defines.')
+
+    def _prepare_for_docker_run(self, docker_target_name, env_path):
+        for f in glob.glob('/{docker_target_name}/*'.format(
+                docker_target_name=docker_target_name)):
+            if env_path in f:
+                try:
+                    b = os.path.basename(f)
+                    if os.path.isdir(f):
+                        shutil.copytree(f,
+                                        '/ml-agents/{b}'.format(b=b))
+                    else:
+                        src_f = '/{docker_target_name}/{b}'.format(
+                            docker_target_name=docker_target_name, b=b)
+                        dst_f = '/ml-agents/{b}'.format(b=b)
+                        shutil.copyfile(src_f, dst_f)
+                        os.chmod(dst_f, 0o775)  # Make executable
+                except Exception as e:
+                    self.logger.info(e)
+        env_path = '/ml-agents/{env_name}'.format(env_name=env_path)
+        return env_path
 
     def _get_measure_vals(self):
         if self.meta_curriculum: